One terminology system across the platform.

A standard handheld optical tool for examining a gem at approximately ten-times magnification. It is useful for inspection but cannot replace all laboratory methods.

A shared descriptive framework for diamond carat weight, color, clarity, and cut. It is useful for comparison, but it is not a complete formula for value or beauty.

A pair of aggregated nitrogen atoms in the diamond lattice, important in FTIR typing of natural diamonds.

A historic marketing slogan associated with De Beers campaigns and the development of the modern cultural meaning of the diamond engagement ring.

Fine wear or roughness on facet edges or other exposed surfaces. It can result from wear, contact, or processing.

Measurement of the wavelengths of electromagnetic radiation absorbed by a sample. In gemology it can help identify chromophores, defects, and patterns associated with identity, color, or treatment.

A smaller stone used to visually emphasize the main element of a piece of jewellery, usually without serving as the primary center of the composition.

An acquisition advantage that provides a better price, access, or information than is typically available to an ordinary market participant.

A very strong, characteristic surface lustre associated with materials of very high refractive index, classically diamond.

The use of machine-learning algorithms or other AI methods for classification, matching, or risk assessment. The result requires validation, a defined scope, and human oversight.

The total purchase budget including the stone, setting, taxes, delivery, commissions, insurance, and other relevant costs.

The total cost up to the point when an item has been safely received and is ready for use, including relevant taxes, shipping, insurance, import costs, fees, and other real transaction costs.

A different structural form of the same chemical element. Diamond and graphite are allotropes of carbon, but different bonding and atomic arrangement give them very different properties.

A metallic mixture consisting of a base precious metal and other elements to achieve the required hardness, color, workability, and other properties.

Controlled heating that allows defects to migrate or reorganize and can change color after irradiation or another process.

Birefringence patterns in nominally isotropic diamond caused by internal stress and deformation of the crystal lattice.

Rules and controls designed to prevent money laundering, including risk identification, monitoring, and reporting under applicable law.

A professional opinion of an item's value for a defined purpose, date, and market context. A laboratory grading report is not automatically an appraisal.

The state of a laboratory-grown diamond crystal immediately after growth, before any post-growth treatment and final cutting and polishing.

An optical tool and viewing environment used to display the distribution of light entering a diamond from different angular zones. It is used in certain light-performance analysis systems.

A square step-cut style with cut corners and a concentric stepped pattern. A protected branded name should not automatically be used for every similar cut.

A Natural Diamond Council program for independent performance testing of specified diamond-verification instruments under a defined protocol.

Sale by competitive bidding under the rules of an auction house or platform. The result reflects a specific channel, commissions, and market moment.

A complex of aggregated nitrogen and a vacancy characteristic of a more advanced stage of nitrogen aggregation in diamond.

A split-sphere type of high-pressure apparatus used for HPHT diamond synthesis and research.

One of the high-pressure press designs used to create HPHT conditions.

A main crown facet of a round brilliant, also often called a kite facet because of its shape.

A setting in which a metal rim partly or completely surrounds the perimeter of the stone. It can provide greater edge protection with a different visual effect.

The difference between the price at which a market participant is willing to buy and the price at which the participant is willing to sell comparable goods.

An optical property of anisotropic materials in which light splits into two rays. Ideal diamond is cubic and optically isotropic, but strain can produce anomalous birefringence.

An external characteristic on the surface of a polished diamond that enters clarity and/or finish interpretation depending on its type and the grading system.

A distributed record technology that can preserve records of events and transfers. It does not by itself confirm the truth of data entered into the system.

Initial shaping of the main facets that establishes the basic geometry of a cut stone before final faceting.

A substitutional impurity associated with type IIb and often with blue to gray-blue color and electrical conductivity, but the presence of boron alone is not evidence of geological origin.

A bow-tie-shaped contrast area that can appear in elongated fancy shapes. Its strength depends on geometry, lighting, and observer position.

A microscopy mode using a bright background or transmitted light, useful for certain transparent and structural features.

The perception of white light returned to the observer from a diamond, including internal and external reflections according to the definition of the system being used.

A broader technical or historical term for the impression of brightness or light return. Its meaning depends on the author and system, so it should be defined when used technically.

A family of cuts designed for strong light return and scintillation. The standard round brilliant is the best-known example, but brilliant is not a synonym for every diamond.

A facet style designed with triangular and kite-shaped facets to produce dynamic light return.

Final faceting and polishing of the smaller facets on brilliant-style stones after the main blocking step.

A brown optical appearance associated with plastic deformation and defect structures in some natural diamonds.

A network of small fractures near the surface caused by impact or pressure, often beneath a damaged point.

The stage of shaping the girdle and basic round or other outline before final faceting and polishing.

A program or contractual policy under which a seller repurchases a previously sold item under specified conditions. The value of such a promise depends on the exact contract and the solvency of the provider.

The conditions under which a seller may offer to repurchase a previously sold product. It is not the same as guaranteed market liquidity or guaranteed value.

A structured record of purchase purpose, budget, must-have criteria, preferences, deal-breakers, and documentation requirements before shortlisting.

A historical or trade term for certain yellow diamonds. It does not replace the full laboratory fancy-color grade.

The authoritative version of content from which derived publications and technical representations originate. Changes require a controlled editorial process.

A unit of gemstone mass. One metric carat equals 0.2 grams; mass alone does not determine how large a stone appears face-up.

A black polycrystalline diamond material with unusual texture and geological history, distinct from typical monocrystalline gem-quality diamond.

Luminescence excited by an electron beam, useful for displaying growth zones and defects in research or specialized laboratory work.

An open depression or void reaching the surface of a polished diamond, often associated with a lost inclusion or damage.

The main or central stone in a jewellery composition.

A term often used in trade for a grading report, but one that can legally and technically imply a different kind of guarantee or certification.

The documented sequence of possession, transfer, or control of an item through the supply chain. Its quality depends on the identity of the links, the controls, and the integrity of the records.

The documented sequence of people, organizations, and control points that physically or administratively handled an item. It is important to the evidentiary reliability of provenance.

A natural fancy-color diamond that can show a temporary reversible color change after heating or after being kept in darkness.

A particular group of natural diamonds whose color temporarily changes after heating or after a period of darkness, with specific gemological behavior.

A trade name for certain brown to yellow-brown diamonds. It is not a universal laboratory color category.

A setting in which a row of stones is placed between two metal walls without individual prongs between each stone.

Localized chipping of a diamond, typically at the girdle, culet, point, or edge. It is a condition or damage feature, not a primary growth form.

A trade or branded term for brown diamonds. Its meaning is not a universal gemological grade category.

A verifiable statement in text that may require evidentiary support, a defined scope, and a currentness designation depending on the nature of the content.

Assessment of a diamond's internal and external characteristics according to their visibility, position, nature, number, and effect under prescribed grading conditions.

A collective term for inclusions and blemishes considered when evaluating clarity.

A laboratory clarity grade assigned under defined viewing conditions and the criteria of the grading system. The name of an individual inclusion is not, by itself, a clarity grade.

A diagram showing the positions of selected clarity characteristics on a laboratory report. A plot is not a complete three-dimensional record of all internal features.

Controlled splitting of diamond along a crystallographically favorable plane. Historically, it was a key stage in rough-diamond processing.

A group of very small inclusions or pinpoints that together can create a hazy or cloudy area. Its effect depends on density, extent, and position.

A surface layer applied to alter the perceived color or another aspect of a stone's appearance. Durability and detection depend on the material and technology used.

A trade name for certain darker brown diamonds. It must not replace the official laboratory color description.

A laboratory color grade assigned under the rules of a particular service and stone population. The D–Z scale is not the same as fancy-color grading.

An additional hue descriptor that modifies the main color name, for example brownish or orangy. Order and grammatical form carry meaning in laboratory nomenclature.

An instrument that quantifies specified color characteristics. Its result is not automatically equivalent to an official laboratory color grade without a validated methodology.

A defect or defect complex in the crystal lattice that absorbs particular wavelengths and can contribute to color.

A transaction or offer involving a sufficiently comparable item used as a market reference, with adjustments for differences in characteristics, channel, and time.

A gemological object made of two or more physically joined parts or materials. The category must be described according to the actual construction.

A term defined by the specific framework of the Kimberley Process and related documents; its formal scope is narrower than the full range of possible violence, human-rights, or sanctions risks.

The difference and spatial relationship between bright and dark areas that contributes to pattern recognition and the impression of scintillation.

An old, stable part of continental lithosphere whose deep root can provide conditions for diamond preservation over geological time.

The limiting angle of incidence above which total internal reflection occurs when light passes from an optically denser to a less dense medium.

The highest level of need for current verification, for example with sanctions, legal restrictions, or other rapidly changing facts.

A configuration of two polarizers at approximately 90° that allows observation of strain patterns and optical anisotropy.

The crown of a polished diamond: the part above the girdle up to the table, composed of different facet groups depending on the design.

The angle of the main crown facets relative to the girdle reference plane, according to the measurement convention of the system being used.

The vertical height of the crown, often expressed as a percentage of a reference dimension.

A mineral or other crystalline inclusion visible inside a diamond. The morphological name alone does not determine its mineral composition.

The periodic spatial arrangement of atoms that defines a material's crystal structure. In diamond it is fundamental to understanding hardness, optics, and defects.

The discipline that studies crystal structure, symmetry, and orientation. In diamonds it is important for growth, morphology, cleavage, and interpretation of defects.

A cubic morphological form of a diamond crystal. External cubic morphology does not change the fact that the material belongs to the cubic crystal system.

The crystal system to which diamond belongs. Its symmetry does not mean every natural crystal must have a cubic external shape.

A multi-anvil high-pressure press of cubic geometry used in some HPHT production systems.

A synthetic zirconium-oxide crystal commonly used as a diamond simulant. Its optical and physical properties differ from diamond.

The lowest termination of the pavilion. It can be a point or a small facet; a separate culet facet traditionally contributes to the facet count of a standard round brilliant.

An editorial status describing how quickly a fact may change and how often it requires renewed verification. It is separate from whether the original claim has achieved evidence closure.

A family of square or rectangular rounded outlines with different brilliant or modified-brilliant facet arrangements.

Jewellery made or configured to a buyer's specific order. It requires a clear specification of design, stone, metal, tolerances, and change or return policies.

The origin of goods determined under applicable customs rules. It is not necessarily the same as the geological or mining origin of a diamond.

An overall assessment of cut quality within a defined laboratory system and its scope. It is not a universal grade for every shape and every laboratory.

A broad concept covering geometric design, execution, and optical behavior of a polished diamond. It is not the same as shape, cutting style, or necessarily a single laboratory cut grade.

The organization of facets, for example brilliant, step, or mixed. It must not be equated simply with the external shape of the stone.

A laboratory diamond-growth method from the gas phase in which carbon is deposited on a growth substrate under controlled conditions.

Diamond growth from an activated gas phase on a diamond substrate at pressures lower than those used in HPHT processes.

A system for describing the relative absence of color in appropriate near-colorless natural diamonds, from D toward Z, according to the rules of the specific laboratory.

Microscope illumination in which the background remains dark while scattered light emphasizes inclusions and internal features.

A historically and currently important diamond company whose role in mining, distribution, and marketing has shaped a large part of the modern industry.

A criterion whose failure automatically removes a candidate from consideration under a predefined Buyer Brief.

Total depth expressed as a percentage of the reference width or diameter according to the system being used.

A professional or trade term for a person or company active in diamond cutting, trading, or valuation, especially in traditional diamond centers.

An organized diamond exchange or trading institution with membership, rules, and market functions.

The name of a specific type of laboratory service or document, not a generic synonym for every report.

The characteristic Raman vibrational line of crystalline diamond near 1332 cm⁻¹. It confirms diamond material, not geological origin.

A diamond crystal substrate on which new diamond material continues to grow in an HPHT or CVD process.

A periodic organized offering of rough diamonds to selected buyers under the rules of a particular producer or sales system.

A material or object that visually imitates diamond but does not have the same crystal and chemical nature. Examples include moissanite and cubic zirconia.

A sales process in which bidders submit offers for a parcel or individual diamonds under the organizer's rules.

Classification of diamond according to the presence and state of certain impurities, primarily nitrogen and boron, typically determined by spectroscopic methods.

A screening or identification device designed for a defined task in distinguishing diamonds, laboratory-grown material, or simulants within its declared scope.

A description indicating that an object visually resembles diamond without making a claim about material identity.

Manipulation of a digital document, record, image, or identifier in order to falsely represent a stone or report.

A digital record or representation of a physical object that can connect identification, imaging, measurement, or transaction data to a specific stone.

The separation of white light into wavelengths because refractive index varies with wavelength. In a cut diamond it contributes to colored flashes, or fire.

A twelve-faced external form that in rough diamonds is often associated with resorption of a primary crystal form.

A composite gemological object made of two joined layers of material. It is not the same as a natural homogeneous stone.

A documented process of identifying, assessing, mitigating, and monitoring relevant risks before and during a business relationship or transaction.

A gem's practical resistance to wear, impact, cleavage, heat, chemicals, and other risks. It cannot be reduced to hardness alone.

A high-pressure rock and an important paragenetic association connected with diamonds and their mineral inclusions.

A rectangular step-cut design with cut corners and prominent stepped facets.

A sanctions restriction associated with a named person or entity and, depending on the regime, with ownership and control rules.

Material introduced into fractures or other spaces after the main growth of the diamond. It does not necessarily carry information about the time when the diamond itself crystallized.

A value claim that, without defined criteria, system boundaries, and data, lacks sufficiently precise technical content.

An editorial status meaning that a claim or chapter has completed the defined source-verification process for a particular snapshot. It does not mean the information will remain current forever.

A date or versioned checkpoint recording how far source verification had progressed for a particular body of content.

The market or channel in which a future sale is expected to take place, for example dealer, auction, private sale, or platform.

An additional facet that is not part of the planned standard arrangement of the design. It can affect symmetry grade depending on position and grading system.

A view of the stone from above, along the table or main presentation axis. It is used to describe appearance, apparent size, and optical pattern.

The visual width and surface impression of a polished stone viewed from above. It is not directly equivalent to carat weight.

An intentionally polished flat surface on a gem. The arrangement, angles, and relationships among facets determine much of the optical behavior of a cut diamond.

Optical doubling of edges or facets visible in doubly refractive materials such as moissanite from certain directions.

The boundary between adjacent facets. Damage or abrasion at a facet edge can be an issue of finish, condition, and durability.

A line or point where two or more facets meet. The precision of junctions contributes to assessment of symmetry and workmanship.

A concept of value that assumes specified market conditions, willing and informed parties, and a defined date and market.

An informal and imprecise expression that can refer to a simulant, a forged document, or a misdescribed product. It is not a recommended professional material category.

A result in which a method fails to flag a sample that, according to its true state, should produce the target result.

A result in which a method incorrectly flags a sample as belonging to the target or suspicious category, depending on the test definition.

An intensity category in GIA fancy-color grading nomenclature, distinct from the general use of fancy for shape.

A GIA fancy-color intensity category describing a darker appearance within fancy-color nomenclature.

A GIA fancy-color intensity category combining strong color with greater darkness within the grading system.

A GIA fancy-color intensity category above Fancy and below Fancy Vivid in the applicable system.

One of the GIA fancy-color intensity categories. It is not equivalent to a D–Z grade and must be read within the fancy-color system.

A very rare fancy-color grade in which the dominant laboratory hue is red without another dominant final hue designation.

In trade and gemological contexts, any diamond shape other than the standard round brilliant, for example oval, pear, cushion, or emerald cut.

A GIA fancy-color intensity category indicating a very strong impression of color under the rules of the grading system.

A diamond whose color is assessed outside the standard D–Z colorless scale using a system that considers hue, tone, and saturation or strength of color.

A term for a fracture or fracture-like inclusion that often appears feather-like under magnification. Its importance depends on size, position, and effect on durability.

Directed illumination through an optical fiber used to emphasize inclusions, surfaces, or a specific area under a microscope.

The proportion of precious metal in an alloy, often expressed in parts per thousand or another applicable marking system.

A group of final workmanship aspects, typically polish and symmetry, depending on the laboratory system.

Perceived colored flashes associated with dispersion and the geometry of light return. Fire is a perceptual effect, while dispersion is a physical property.

Visible colored flashes associated with dispersion of light in a polished diamond. Fire contributes to optical appearance but is not the only measure of cut quality.

The highest GIA clarity category for a diamond with no inclusions or blemishes visible to a skilled grader at 10× magnification under prescribed conditions.

Emission of visible light during exposure to suitable excitation radiation, often ultraviolet. It stops very quickly after excitation ends.

A crack or discontinuity in diamond. In clarity nomenclature, some fractures may be described as feathers depending on appearance.

Introduction of foreign material into surface-reaching fractures to reduce their visibility. It can materially affect care requirements and disclosure.

A treatment in which material is introduced into surface-reaching fractures to reduce their visibility. It must be clearly disclosed because it can affect appearance and care.

A principle of free, prior, and informed consent relevant to the rights of Indigenous communities and projects that affect them.

An infrared spectroscopic method widely used for diamond typing and detection of certain impurities, defects, and treatment indications.

The lateral or lower structural zone beneath a set stone that connects setting elements and affects profile, access, and maintenance.

A group of methods used to determine the timing of geological processes. For diamonds, age is often estimated through datable inclusions rather than directly from pure diamond carbon.

A conclusion or claim about the geographic area from which a natural diamond originates. It must be tied to the methodology, scope, and confidence level of the specific service or evidence chain.

The peripheral zone between the crown and pavilion of a polished diamond. Girdle thickness and finish affect proportions, durability, and weight retention.

A historical name associated with Indian mining and trading regions and legendary diamonds. Geographic origin must not be inferred automatically from the physical type of a stone.

A unit of gold-alloy fineness on a 24-part scale. It is not the same as carat, the unit of gemstone mass.

An optically active center associated with the neutral vacancy, often important in the context of radiation-induced color changes and laboratory identification.

A laboratory document describing examination and/or grading results for a specific item within the scope of a particular service. It is not automatically a market valuation or proof of ownership.

Visible or optical traces of growth irregularity or deformation in diamond that can be internal, surface-related, colored, or reflective.

Graphitic or graphite-like carbon material inside a diamond or along fractures, often dark in appearance.

The technological method by which a crystal was laboratory-grown, primarily HPHT or CVD in the commercial gemological context.

A crystallographically defined growth region associated with a particular crystal face or direction. Different sectors can incorporate impurities differently.

A spatial region of a crystal recording a phase or change in growth conditions. It can be expressed optically, chemically, or through luminescence.

An optically active nitrogen-vacancy-related defect that can contribute to green, yellow, or other luminescence or spectral features depending on context.

A design in which smaller stones surround a center stone or another central area.

A fancy heart-shaped outline whose visual quality strongly depends on lobe symmetry, the cleft, and the lower point.

An optical pattern that can appear in very precisely aligned round brilliant diamonds under an appropriate viewer. It is not a standalone universal laboratory cut grade.

Mass retained in proportions or geometry that contributes little to face-up size or optical effect but increases carat weight.

The period during which an asset is intended to be held before a potential sale. It matters for costs, risk, and the investment thesis.

A stable internal identifier for an entity such as a chapter, term, or visual. The identity of the entity is separate from its URL address.

An abbreviation that can describe a growth method or, in another context, a treatment. The full meaning and function of the process must be clear from the sentence.

A laboratory diamond-growth method using high pressures and temperatures, designed around conditions in which diamond is thermodynamically stable.

Application of high pressure and temperature to an existing diamond to alter specified optical or structural properties, most commonly color.

The basic category of perceived color, for example yellow, blue, or pink. In fancy-color nomenclature it can be modified by additional hue descriptors.

An object combining a natural diamond portion with laboratory-grown diamond material or another hybrid construction. It requires a precise description of its architecture.

An analytical conclusion confirming material identity or other defined properties within the valid scope of the method.

A material or object that imitates the appearance of diamond but is not diamond material. In practice it overlaps with the concept of a diamond simulant depending on the standard and context.

The GIA clarity group I1, I2, and I3, in which inclusions can be obvious at 10× magnification and may affect transparency or durability.

An internal characteristic of diamond: mineral, crystal, fluid, fracture, growth structure, or another feature that can carry gemological and geological information.

A liquid or fluid phase trapped during or after crystal growth. In diamonds it can carry information about deep fluids and geological processes.

A portion of the original rough surface that extends below the geometrically expected surface of a polished stone and may continue inward.

An estimate of the cost to replace an item under the insurer's and market's conditions; it is not the same as cash resale value.

Internal lines, zones, or textures associated with growth or strain that are observed within a diamond.

A laser method that creates internal microstructures or channels without a conventional surface drill hole, depending on the process.

A GIA clarity category with no inclusions visible at 10× magnification under prescribed conditions, while certain surface blemishes may be present.

An explicit hypothesis explaining why a particular diamond might preserve or increase value, including assumptions about rarity, demand, time horizon, costs, and exit market.

Exposure of diamond to ionizing radiation to create or alter lattice defects and thereby change color.

Treatment processes that can change diamond color by creating and/or moving defects in the crystal lattice.

An elongated lower termination of some step-cut or other fancy designs, rather than a single culet point or facet.

Material lost as the width of a cut during sawing or laser separation. It forms part of the economics of polished yield.

An international certification system for cross-border trade in rough diamonds among participants under the defined Kimberley Process framework.

An ultrabasic volcanic rock that can transport diamonds from the deep mantle toward the surface. Kimberlite is not where most diamonds form.

An included crystal that reaches the surface of a polished diamond and can interrupt the surface continuity of a facet.

A set of procedures for identifying and verifying a customer or business partner in order to manage legal, sanctions, and other risks.

A microdestructive analytical method for highly sensitive measurement of elemental composition. It is not a routine first step for every diamond object.

A colloquial abbreviation for laboratory-grown diamond. It is not preferred in formal technical writing because it can be ambiguous and must not be used for simulants.

A qualified English term permitted in some standards and jurisdictions for technologically produced diamond.

A diamond produced by technological growth, most commonly by HPHT or CVD. Crystallographically it is diamond and is not a simulant merely because it is not of natural geological origin.

A volcanic rock that in certain geological systems can host or transport diamonds, but is much less commonly associated with economic diamond deposits than kimberlite.

The use of a laser-created channel to access a dark inclusion or area that may then be modified.

A treatment in which a laser creates a channel to an inclusion so that it can be removed or altered to reduce visibility. Such treatment should be disclosed.

A laser inscription on the girdle or another accessible surface, often containing a report number or disclosure. It can assist stone matching but is not impossible to remove.

A microscopic inscription made by laser, often on the girdle, that may contain a report number or another marking. The inscription must be matched to the physical item and document.

A departure from the ideal atomic arrangement in a crystal, such as a vacancy, impurity, or defect complex. It can affect color, luminescence, and spectra.

The ratio of maximum face-up length to width. It strongly changes the visual character of fancy shapes, but there is no single universally ideal ratio.

A methodology for assessing environmental impacts across defined stages of a product's life cycle using specified system boundaries and a functional unit.

Light that exits a diamond in directions that do not contribute to the desired face-up return toward the observer under the specified lighting environment.

The ways in which a polished diamond returns and distributes light to the observer, including brightness, fire, scintillation, pattern, and contrast.

A description of the amount and distribution of light that, after interacting with the facets, exits a diamond toward the observer or measurement system.

The practical ability to sell an asset within a reasonable period and an acceptable price range. The retail purchase price is not evidence of future liquidity.

The ability to sell an asset within a reasonable period with limited price impact. For individual diamonds this can differ greatly from the retail visibility of the product.

A natural diamond formed in the lithospheric mantle, typically beneath stable cratons. It differs from superdeep diamonds in its geological formation environment.

A stone that is not set in jewellery, making its surfaces and geometry more accessible for measurement and observation.

One of the lower-half facets adjacent to the girdle on the pavilion of a standard round brilliant.

Imaging the spatial distribution of fluorescence or phosphorescence to reveal growth patterns, sectors, and other features.

A qualitative description of the appearance of light reflected from the surface of a mineral or gem. Diamond is traditionally described as having adamantine lustre.

A flattened triangular diamond twin formed on a specific twinning plane. It is important in rough morphology and cutting planning.

The layer of Earth between the crust and core in which the great majority of natural diamonds form, at depths and conditions far removed from the surface.

An elongated fancy shape with pointed ends. Evaluation includes outline symmetry, length-to-width ratio, and bow-tie behavior.

A reference diamond from a standardized set used for visual D–Z color grading under controlled conditions.

A conclusion about which material is physically and chemically present. For a diamond-like stone, it comes before the question of natural versus laboratory-grown origin.

A trade term for small polished diamonds that are often handled and screened in large groups. Size boundaries vary by market context.

A trade arrangement in which goods are provided for inspection or sale without final transfer of ownership until agreed conditions are met.

The legal or business entity that actually sells goods and enters into the transaction with the buyer. On a marketplace, the merchant, platform, payment provider, and shipper may be different entities.

The metallic phase in a typical HPHT growth process that facilitates dissolution of carbon and its transport toward the seed crystal.

A metallic inclusion or particle with a metallic appearance; it is particularly relevant in some HPHT-grown material, but metallic inclusions can also occur in natural diamonds.

A CVD configuration in which microwave energy sustains plasma above a heated diamond substrate.

The place or jurisdiction in which a natural diamond was mined. It can be relevant to sanctions and due diligence and can differ from the country of cutting or customs origin.

A design combining elements of brilliant and step facet arrangements or other distinct facet logics.

Silicon carbide commonly used as a diamond simulant. Its physical and optical properties differ from diamond and it can be identified with appropriate tests.

A status for content that is periodically rechecked because professional, market, or institutional conditions may change.

A stone set in jewellery. Metal and construction can restrict access, measurements, mass determination, pavilion observation, and the behavior of some testers.

A nitrogen-related defect associated with characteristic absorption and blue fluorescence in some natural diamonds.

A remnant of the original rough crystal surface intentionally left on a polished stone, often at or near the girdle.

Diamond formed by natural geological processes in Earth or, rarely, by extraterrestrial processes. Origin cannot be concluded from the carbon chemical formula alone.

A thin elongated inclusion with a needle-like appearance. The name describes morphology, not necessarily chemical identity.

The most important impurity in many natural and laboratory-grown diamonds. Its aggregation state is central to atomic type and many spectral features.

A diamond crystal-lattice defect consisting of a nitrogen atom adjacent to a vacancy. It is important in spectroscopy, quantum sensing, and color research.

Blocking part of the incoming or outgoing light by the observer, camera, or instrument, which can create characteristic dark patterns.

A classic diamond crystal form with eight triangular faces. In rough it can be ideal, modified, resorbed, or combined with other forms.

A historical family of round brilliant-style cuts predating modern round-brilliant standardization and typically showing different proportions and facet patterns.

A historical cushion-like brilliant style with a hand-shaped outline, larger culet, and proportions characteristic of older cutting techniques.

A digital sales record for a particular diamond or piece of jewellery that may combine price, laboratory number, photographs, video, and sales descriptions. A listing is not by itself proof of the physical stone's identity, custody, or current availability.

A term whose meaning depends on context: it can refer to geological, mining, trade, customs, or another legal origin. These categories are not automatically the same.

A laboratory conclusion about whether observed color is natural or the result of treatment, within the scope of the specific service. It is not the geographic origin of the stone.

An elongated rounded fancy shape. Visual balance depends on outline, length-to-width ratio, and bow-tie behavior.

A set of mineralogical and geochemical relationships indicating the environment of formation or evolution of a rock and its inclusions. For diamonds, peridotitic and eclogitic associations are commonly distinguished.

A screening result meaning that a sample met the criteria of a particular method within its validated scope. It must not be expanded into claims the device was not designed to confirm.

The relative arrangement of bright and dark areas in the face-up appearance of a diamond, produced by a combination of internal and external reflections.

Dense setting of small stones with tiny metal beads or prongs so that the surface appears paved with gems.

The part of a polished diamond below the girdle extending toward the culet or another lower termination.

The lower part of a polished diamond below the girdle. Its facets and angles strongly affect the path of light and overall optical performance.

The angle of the main pavilion facets relative to the girdle reference plane, important to the optical geometry of a round brilliant.

The vertical depth of the pavilion, often expressed as a percentage of a reference dimension.

A teardrop-like fancy shape with one rounded end and one pointed end.

An ultrabasic mantle rock and an important paragenetic association in the study of inclusions and the origin of natural diamonds.

Extended emission of light that can continue after the excitation radiation has been removed.

Light emission after optical excitation; spectral PL analysis is highly sensitive to defects and centers important in diamond identification.

A mechanism that reliably connects a digital record to a specific physical stone, for example through inscription, imaging, or a measurement fingerprint.

A very small point-like inclusion, often a tiny crystal that appears as a dot at a given magnification. Many pinpoints together can form a cloud.

An ionized or strongly activated gas phase that, in a CVD reactor, provides the chemical species required for deposition of diamond carbon.

Permanent deformation of the crystal lattice caused by stress. In diamond it can produce graining, strain patterns, and be associated with certain colors.

A precious metal used in jewellery in different alloys and finenesses. Mechanical behavior depends on the specific alloy and workmanship.

An instrument using polarizers to observe optical isotropy or anisotropy and strain. In diamond it can reveal anomalous birefringence.

An assessment of facet-surface finish, including polishing lines, scratches, and other surface features under the rules of the laboratory system.

A laboratory assessment of facet-surface polishing quality according to the criteria of the specific grading system.

A diamond after cutting and polishing into its final gemological form. “Polished” describes the manufacturing stage, not a quality grade.

The ratio of finished polished-diamond mass to starting rough mass. Yield is economically important but should not be optimized separately from the quality and value of the final stone.

A treatment applied after laboratory growth is complete to alter a property such as color. It does not change the original growth-method classification.

A source originating directly from the institution, author, research, regulation, standard, or data owner relevant to a claim.

A usually square or rectangular fancy brilliant or mixed design with sharp corners and a distinctive pavilion architecture.

A legal restriction associated with a particular type of goods, tariff category, origin, or another product criterion.

A setting in which metal prongs or claws mechanically hold the stone. Their number, profile, and thickness depend on the design and risk profile.

Measurable geometric relationships among facets, angles, and dimensions of a polished diamond. Their effect should be assessed as a system, not as one isolated number.

An inclusion whose mineral precursor existed before diamond growth, although the present boundary between phases can be more complex than a simple chronological label.

The documented history of origin, ownership, transfer, and other relevant events associated with an object. It is not a synonym for geological origin.

A square or rectangular fancy cut with cut corners and a brilliant or mixed facet arrangement, distinct from the step-facet logic of an emerald cut.

A spectroscopic method analyzing inelastic light scattering, enabling characteristic identification of materials and specific phases.

The rhenium–osmium isotopic method that can be applied to suitable sulfides associated with diamonds for geochronological conclusions.

Re-cutting an already processed diamond to change shape, proportions, finish, or remove damage, with possible loss of mass.

A screening result in which the sample is not resolved as pass within the validated scope and requires additional analysis. It is not a diagnosis of laboratory-grown, treated, or simulant material.

Illumination directed onto an object's surface to observe polish features, surface characteristics, inscriptions, and construction.

A change in the direction of light as it passes between media of different refractive index, except under particular incidence geometries.

A ratio describing how the speed and direction of light change when it enters a material. Diamond has a very high refractive index in the visible range.

The visual contrast of a clarity characteristic against the surrounding diamond. In some systems it contributes to assessing the characteristic's effect on grade.

Closeness of results from repeated measurements or assessments under the same or very similar conditions, according to a defined methodology.

A laboratory-report field for additional conclusions, disclosures, or information that is not part of the main grade fields.

Fraud that misuses a real or fabricated laboratory report, number, QR code, PDF, or inscription to represent another stone as the documented item.

A unique or operational identifier for a laboratory document used to verify the record and match it to a stone.

Checking a laboratory record through the institution's official channel to confirm that the number and published data correspond to the recorded document.

Closeness of results when relevant conditions such as operator, laboratory, or equipment change, under a defined protocol.

The amount that can realistically be achieved by selling an existing item in a particular secondary market after accounting for costs, time, and risk.

Partial dissolution and reshaping of a diamond crystal's surface during residence in the mantle or transport toward the surface.

A sourcing process that defines and manages relevant environmental, social, human-rights, legal, and governance risks in the supply chain.

The selling price to an end customer in a specific channel and at a specific time, including margins, service, taxes, and other market elements as applicable.

Application of a thin rhodium layer to jewellery for color, lustre, or surface properties. The coating can wear over time.

A consumer's legal right, under prescribed conditions, to withdraw from certain distance contracts. It must not be equated with a seller's voluntary commercial return policy.

The upper structure of a ring that carries or integrates the setting for the main stone.

The circular part of a ring that surrounds the finger and carries the upper structure.

The transitional part of a ring between the shank and the head or setting, often important both structurally and decoratively.

A historical cut with a flatter base and a series of triangular upper facets rising toward the top, without the conventional pavilion of a modern brilliant.

An uncut diamond crystal or piece of diamond material before final cutting and polishing.

An uncut or minimally processed diamond before final planning and cutting into a polished gem.

The process of deciding how to obtain one or more polished products from a rough diamond while balancing weight, quality, risk, and expected value.

A round brilliant-style design with typically 57 or 58 traditionally counted facets, depending on whether a culet facet is present. Specific cut-grade methods can be restricted to this category.

Verification of whether a transaction, goods, person, ownership structure, service, or jurisdiction is covered by an applicable sanctions regime.

The relative saturation or intensity of a color. Together with tone and hue, it contributes to the perceived strength of fancy color.

Cutting a rough diamond with a saw or laser system to divide the crystal before further shaping.

The dynamic pattern of bright and dark flashes that changes as the diamond, light source, or observer moves.

The defined range within which a claim, method, laboratory service, or body of evidence is valid. A conclusion must not be automatically extended beyond that scope.

A sorting or checking process used to quickly identify items that meet a criterion or require further analysis. Screening is not necessarily final identification.

A source that analyzes, reports, or synthesizes primary data and documents. Its quality depends on methodology, expertise, and transparency.

The net amount remaining to the seller after commissions, discounts, logistics, taxes, and other exit costs.

The ability of a test to detect the target category for a defined sample population and set of conditions.

A sanctions or regulatory restriction on providing a particular service connected with goods, an entity, or a jurisdiction.

The construction that holds and positions a diamond or other gem in jewellery. The term refers to the setting method, not the entire piece of jewellery.

The external face-up outline of a polished diamond, for example round, oval, pear, or marquise. Shape is not the same as facet arrangement or cut quality.

A narrowed set of candidates that satisfy the basic criteria and proceed to more detailed comparison.

A stone set beside the main stone as part of the jewellery design.

A trade status associated with periodic rough-diamond sight sales by certain producers or systems. Historically it is strongly associated with the De Beers model.

A simpler brilliant-style arrangement with fewer facets, often used for small diamonds.

The GIA clarity group comprising SI1 and SI2, with inclusions noticeable at 10× magnification under the laboratory's criteria.

The samarium–neodymium isotopic method applicable to certain mineral inclusions and paragenetic systems.

A jewellery design emphasizing a single main stone, especially in a ring. The term by itself does not specify the setting type.

A grouped set of sources and verification work used to close a particular topic or chapter in an editorial workflow.

A bonding model in which each carbon atom in an ideal diamond lattice is tetrahedrally bonded to four neighboring atoms.

A less formal description of light flashes seen as the stone, light source, or observer moves. In technical writing, scintillation is more precise when referring to the defined optical effect.

The dimensionless ratio of a sample's density to the density of water under defined conditions. It is useful gemological information but is rarely sufficient as a standalone identification test.

The ability of a test to correctly avoid flagging samples that do not belong to the target category, according to a defined protocol.

A group of methods studying interactions between matter and electromagnetic radiation. In gemology it is used for material identity, defects, treatments, and the origin of certain features.

A status for content not expected to change quickly, while still remaining under version and editorial control.

A star facet on the crown of a standard round brilliant, positioned between the table and the main crown facets.

Cleaning with a jet of steam that can be effective for suitable diamond jewellery but requires assessment of the setting, treatments, and condition of the item.

A cutting style with rows of elongated, approximately parallel facets arranged in steps, as in an emerald cut.

The process of physically linking a stone to a laboratory document by comparing inscription number, mass, dimensions, plot, and microscopic characteristics.

Elastic or residual deformation of the crystal lattice that can appear through optical and other measurable effects. It is not the same as a fracture.

A natural diamond formed deeper than the typical lithospheric mantle, including the mantle transition zone and lower mantle.

Growth lines or irregularities visible on a facet surface and related to the crystal structure.

A broad term for processes that alter a gem's surface or very shallow layer to affect appearance or another property.

A sustainability claim must state the relevant environmental, social, and economic criteria, system boundaries, time span, and data.

An assessment of geometric regularity and mutual alignment of facets, outline, and cutting features according to laboratory criteria.

A laboratory assessment of geometric regularity, position, and relationships among facets and specified measurement features under a particular system.

An inclusion formed together with the host diamond in a related growth process. The term should be used cautiously where the chronological relationship has not been directly established.

A standardized English term used in part of the international nomenclature for diamond produced by a human technological process.

Laboratory-produced silicon carbide commonly used as a diamond simulant. Synthetic refers to moissanite; it does not make the material a synthetic diamond.

The defined boundary of processes and stages included in an analysis, for example an LCA or sustainability comparison. Different boundaries can produce non-comparable results.

The large top facet of a polished diamond. It should not be confused with the measurement parameter table percentage.

The largest upper facet of most standard polished diamonds. Its relative diameter or width is an important part of proportion description.

The relative size of the table facet expressed as a percentage of a reference dimension according to the rules of the specific measurement system.

A controlled spatial temperature difference that drives transport of dissolved carbon toward the growth zone in an HPHT system.

A handheld instrument that evaluates a stone's thermal behavior as a screening aid. The result can be ambiguous and does not replace full identification.

A design with three prominent stones, typically one center stone and two side stones.

A status for content that can change within a relatively short period, making the date of factual review materially important.

The relative lightness or darkness of a color. In gemological color analysis it is distinguished from saturation and hue.

The sum of the carat weights of multiple stones in a piece of jewellery within the stated scope. It is not the same as the weight of an individual center stone.

The total vertical dimension of a polished diamond from the table to the lowest part of the pavilion or the culet facet.

An optical phenomenon in which light at a boundary with a less optically dense medium is completely reflected when the angle of incidence exceeds the critical angle.

The ability to follow a documented chain of events, identity, or origin through a supply chain. Its quality depends on the integrity of input data and system controls.

The ability to track an item and associated data through a defined chain, system, or process stages. It does not by itself guarantee that the original data were true.

A diamond whose property, such as color or fracture visibility, has been altered by a subsequent process. It can be of natural or laboratory-grown origin.

An intentional intervention that changes the appearance, color, clarity, or another property of an existing stone. Relevant treatments must be clearly disclosed.

Clear disclosure that material has undergone treatment and, where necessary, the type or consequences of the treatment. Disclosure is a communication obligation, not evidence of value.

A market expression for the combination of Excellent cut, Excellent polish, and Excellent symmetry on a document that uses those categories.

A composite object made of three physically joined layers or parts.

An irregular group of tiny crystals, pinpoints, or graining associated with twinned growth and deformation.

A diamond in which measurable nitrogen is predominantly aggregated. It is common among natural diamonds and includes multiple subtypes.

A diamond with predominantly isolated substitutional nitrogen. It is rare in nature but can be common in certain HPHT-grown material.

A diamond without measurable nitrogen impurities in standard FTIR classification. Type IIa occurs both naturally and in laboratory-grown diamonds.

A diamond in which boron is an important measurable impurity. It can show electrical conductivity; both natural and laboratory-grown examples exist.

Cleaning in liquid using ultrasonic vibrations. It is not appropriate for every treated stone, weakened setting, or combination of materials.

Electromagnetic radiation with wavelengths shorter than visible light. In gemology it is used to excite fluorescence and other luminescence responses.

Quantified or qualitative uncertainty associated with a measurement, grade, identification, or conclusion. It should be communicated in proportion to the importance of the decision.

A merchant program that, under specified conditions, credits part of a previous purchase value toward another product.

One of the upper-half facets adjacent to the girdle on the crown of a standard round brilliant.

Absorption spectroscopy in the ultraviolet, visible, and near-infrared regions, useful for color, defect centers, and identification.

A missing atom at a crystal-lattice site. Vacancies and their complexes can create optically active color centers.

The GIA clarity group comprising VS1 and VS2, for minor inclusions more readily observed at 10× than those in the VVS categories.

The GIA clarity group comprising VVS1 and VVS2, for inclusions that are very difficult to observe at 10× magnification.

The House of Kacinari layer for structured linking of figures, photographs, diagrams, and archival objects with description, credit, license, and source information.

A gold alloy designed for a lighter or white appearance, often with rhodium plating. Composition and color depend on the alloying elements.

A price in a wholesale or trade channel under defined transaction conditions. It cannot be mechanically compared with a retail price without adjusting for context.

X-ray imaging that can use differences in absorption and structure for specific gemological or forensic tasks.

A crystal that did not crystallize from the magma carrying it but was incorporated from an earlier environment. Diamonds in kimberlite are typical xenocrysts.

A rock fragment captured and transported by magma from a deeper environment. Mantle xenoliths provide direct context for studying diamond host rocks.