What Is a Laboratory-Grown Diamond?

A laboratory-grown diamond is not an imitation of diamond. It is crystalline diamond material produced through a human-controlled technological growth process, most commonly the HPHT or CVD method.

That statement has two equally important parts. The first concerns the material: its lattice is diamond, and the material can possess diamond’s fundamental physical properties. The second concerns origin: the crystal did not form through a natural geological process within Earth.

Considering only one of these two aspects leads to error.

Material identity is not the same as origin

Four categories must be kept separate:

Natural diamond — diamond material formed through a natural geological process.

Laboratory-grown/synthetic diamond — diamond material produced through technological growth.

Treated diamond — an existing diamond whose property, such as color or the appearance of a fracture, has been altered by a subsequent process. Either a natural or a laboratory-grown diamond can be treated.

Simulant — a material that imitates diamond’s appearance but is not crystalline diamond material. Cubic zirconia and moissanite are common examples of simulants.

“Is it diamond?” and “How did it form?” are two different questions.

What “the same material” means

A laboratory-grown diamond can share the following characteristics with a natural diamond:

• an sp³-bonded carbon lattice;
• very high hardness;
• a high refractive index;
• strong dispersion;
• high thermal conductivity;
• the characteristic Raman signal of diamond.

However, the growth process leaves different statistical patterns in impurities, growth sectors, luminescence, lattice strain, and other microscopic or spectroscopic features. Laboratory identification is based precisely on these differences.

HPHT and CVD—the two principal methods

HPHT growth uses very high pressures and temperatures, a carbon source, a diamond seed, and usually a metal solvent-catalyst. Within a controlled temperature gradient, carbon dissolves and crystallizes on the seed.

CVD growth takes place at much lower pressure. A gas mixture—typically rich in hydrogen and containing a hydrocarbon such as methane—is activated by plasma. Reactive carbon species reach a heated diamond substrate and incorporate carbon into the crystal layer by layer.

These two technologies are discussed in detail in Chapters 49 and 50.

[VISUAL 48.1: Natural diamond, HPHT, and CVD—the same diamond material, three different formation pathways]

Seed, growth, and the as-grown state

Both principal technologies for commercial single-crystal growth use a diamond seed as the initial crystalline substrate.

The seed is not a finished stone that is merely “coated.” New diamond material grows from it in crystallographic continuity. Growth produces an as-grown crystal or plate that can subsequently be cut, treated, and polished.

It is therefore necessary to distinguish among:

• growth method;
• as-grown state;
• post-growth treatment;
• final polished product.

For example, a CVD diamond may undergo HPHT treatment after growth to alter its color. This does not make it an “HPHT-grown” diamond; its growth method remains CVD, while HPHT in this case is a treatment.

Laboratory-grown diamonds are not uniform commodities

A controlled process does not mean that every crystal is perfect. Laboratory-grown diamonds vary in:

• color;
• clarity;
• lattice strain;
• impurity distribution;
• growth sectors and zones;
• post-growth processing;
• cutting quality;
• weight and dimensions.

Production can be controlled, but it does not produce atomically identical stones.

Diamond type is not proof of origin

Many gem-quality CVD diamonds contain very little measurable nitrogen and are type IIa. HPHT material is often type Ib, but it can also be type IIa or IIb, depending on the process and intended result.

At the same time, natural type IIa and IIb diamonds also exist. FTIR typing can therefore provide highly useful screening data, but it is not a final verdict on natural versus laboratory-grown origin.

Why the unaided eye often cannot provide a reliable distinction

A well-cut laboratory-grown diamond can look like a natural diamond with the same basic visual characteristics. Color, clarity, fire, and scintillation are not in themselves evidence of geological origin.

The claim that “an experienced jeweler can tell immediately” is not reliable as a general rule. Microscopic features can be indicative, but modern identification increasingly requires spectroscopic and luminescence analysis.

A standard thermal diamond tester primarily helps confirm that the material is diamond; it does not prove natural origin.

A simulant is not a laboratory-grown diamond

Moissanite is silicon carbide. Cubic zirconia is zirconium oxide. Both can visually imitate diamond, but their chemistry, structure, and physical properties differ.

It is therefore incorrect to call a simulant a “lab diamond.” A laboratory-grown diamond and a diamond simulant belong to different categories.

[VISUAL 48.2: Four-part classification—natural diamond | laboratory-grown diamond | treated diamond | simulant]

Terminology depends on the standard and jurisdiction

This book uses laboratory-grown diamond as its primary term. In international documents, the terms laboratory-grown, laboratory-created, and synthetic diamond may appear, depending on the applicable nomenclature system.

As of the factual cutoff of August 7, 2026:

• ISO 18323:2015 remains the published international standard for consumer terminology relating to diamonds and was reconfirmed on February 19, 2026;
• the CIBJO Diamond Blue Book 2024-1, effective since October 2024, permits synthetic, laboratory-grown, and laboratory-created as synonymous qualifiers within its nomenclature system and requires clear disclosure;
• the U.S. FTC Jewelry Guides permit clear qualifiers such as laboratory-grown and laboratory-created when the material has essentially the same optical, physical, and chemical properties as a mined diamond; the Jewelry Guides are industry guidance interpreting the application of Section 5 of the FTC Act, not a standalone law;
• in July 2026, the CIBJO Diamond Commission proposed making synthetic the preferred term and limiting the 4Cs to natural diamonds, but as of the August 8, 2026 cutoff, this remained a pre-congress proposal, not an adopted amendment to the Blue Book.

Because standards can change, the web edition must keep this note dated.

Reports and laser inscriptions

A grading report can confirm laboratory-grown origin and provide information within the scope of the specific service. A laser inscription on the girdle can link a stone to a report number and disclosure.

However, an inscription is not sufficient without a physical match. It can be removed, polished away, misread, or counterfeited. The document, weight, dimensions, inscription, and microscopic features should all agree.

Current GIA practice is not a universal standard

Since October 1, 2025, GIA has used an overall Premium or Standard Quality Assessment classification for eligible colorless to near-colorless laboratory-grown diamonds, rather than its traditional natural-diamond nomenclature. This is the policy of one institution during a particular period, not a definition of the material itself or a rule followed by every laboratory.

A full review of laboratory systems and reports appears in Chapters 54 and 75–77.

Origin is not a value judgment

Material identity does not automatically determine rarity, market price, resale liquidity, environmental footprint, or social impact.

Natural and laboratory-grown diamonds have different production chains and different economics. Any claim that one category is “always more ethical,” “always greener,” or “always a better investment” requires separate data, methodology, and a dated factual cutoff.

Those questions are addressed in Chapters 55–56 and 94–95.

Professional product-verification protocol

1. Read the full product name.
2. Determine whether the material is described as natural, laboratory-grown, or simulated.
3. Separately check for any treatment disclosure.
4. Verify the institution, date, and type of report.
5. Compare the documented weight and dimensions with the stone.
6. Check the laser inscription when present.
7. Physically match inclusions and other identifying features.
8. For jewelry, determine whether all stones have the same origin.
9. Keep quality claims separate from origin claims.
10. Verify environmental, ethical, and provenance claims separately.

Chapter summary

• A laboratory-grown diamond is diamond material of laboratory-grown origin.
• It is not a simulant merely because it is not natural.
• Material identity and mode of formation are two separate axes.
• HPHT and CVD are the two principal commercial growth technologies.
• A seed is the crystalline substrate on which new diamond material grows.
• The as-grown state must be distinguished from post-growth treatment.
• Laboratory-grown diamonds vary in color, clarity, defects, and processing.
• Diamond type is not a conclusive origin test.
• The unaided eye and a standard diamond tester are often insufficient to determine origin.
• Moissanite and cubic zirconia are simulants, not laboratory-grown diamonds.
• Terminology must be tied to a specific standard, jurisdiction, and date.
• Quality, value, sustainability, and origin must be evaluated as separate questions.

[VISUAL 48.3: Life cycle of a laboratory-grown diamond—seed → growth → as-grown → post-growth treatment when needed → cutting and polishing → laboratory verification]

[VISUAL 48.4: Documentation layers—material origin | treatment status | quality assessment | physical match to the stone]