Clarity Plots, Clarity, and Durability
A clarity plot looks like a map of a diamond. That is precisely why it is easy to attribute more precision to it than it possesses. A plot is a selected two-dimensional representation of important clarity characteristics, not a computed tomography scan of the stone, a scale drawing, a complete list of every microscopic detail, or a forecast of future breakage.
Its true value emerges when it is read together with the clarity grade, report comments, actual microscopic examination, transparency, and the question of durability.
What a Plot Shows
On a conventional diagram, a laboratory may mark selected internal and surface characteristics viewed through the crown and/or pavilion. A symbol describes the type and approximate position of a characteristic, but need not reproduce its full 3D shape, actual depth, openness to the surface, or all reflections through the facets.
Two rules therefore have great practical value:
A plot is not drawn to scale.
A plot is not a complete 3D map of a diamond.
Inclusion, Blemish, and Finish
An inclusion is an internal clarity characteristic or a feature that extends into the stone’s interior. A blemish is a surface characteristic. Finish encompasses the quality of polish and symmetry and should not automatically be conflated with clarity.
The same visual region may require careful determination of its relationship to the surface. For example, a fully enclosed crystal is not the same as a knot that reaches the surface; an internal feather is not the same as an open fracture.
Five Factors in Clarity Assessment
The GIA clarity-grading system considers five interrelated factors:
- size of the characteristic;
- number of relevant characteristics;
- position;
- nature of the characteristic;
- color or relief, meaning how clearly it differs from its surroundings.
This is not an arithmetic formula. A large central characteristic may have a greater effect than several tiny peripheral ones. Reflections may visually magnify the impression of one inclusion. The type of characteristic matters because it determines how the feature behaves optically and how it relates to the surface.
Grade-Setting Characteristic
One or several characteristics may effectively set the boundary of the clarity grade. This does not mean that the first term listed in a laboratory comment is always the sole reason for the grade, nor that it is the most important feature for identifying the stone.
Clarity grading is an integrated assessment under standardized magnification and conditions. The detailed scale remains in Chapter 28.
A Plot as an Identification Fingerprint
The combination of characteristics is often highly useful for matching a stone to its documentation. Distinctive crystals, feathers, clouds, naturals, or other characteristics may together form a recognizable pattern.
A plot, however, is not proof of ownership. A stone may be recut, damaged, or oriented differently; a report may be counterfeit; two stones may coincidentally have similar simple diagrams. Professional matching also incorporates weight, dimensions, shape, laser inscription when present, and the actual microscopic relationships.
[VISUAL 47.1: Plot as a 2D map—crown and pavilion views versus the actual 3D positions of the same characteristics]
Why Not Everything Present Appears on the Plot
Laboratories use different formats and plotting rules. Some tiny or numerous characteristics may be summarized in comments. Some features may be omitted if they are unnecessary for understanding the grade or the identification pattern. A digital or abbreviated report may have a different scope from a full diagram report.
The absence of a symbol is therefore not proof that a microscopic characteristic does not exist.
Clarity and Transparency Are Not the Same
Clarity describes the relative presence and significance of inclusions and blemishes under the rules of a particular system. Transparency describes how well light passes through the stone without diffuse scattering or cloudiness.
Clarity and transparency can diverge in either direction:
- a relatively high clarity grade with a broadly distributed cloud or graining that reduces transparency;
- a lower clarity grade because of one clearly bounded inclusion, with very good transparency throughout the rest of the stone.
The term eye-clean is a trade description and has no universal laboratory definition. It depends on distance, eyesight, illumination, orientation, and the observer’s expectations.
Clarity and Durability Are Not the Same
A clarity grade does not express a percentage probability of breakage.
Factors of particular importance to durability include:
- type of characteristic;
- whether it touches the surface;
- whether it is near the girdle, a corner, point, culet, or keel line;
- orientation relative to cleavage planes;
- existing branching of the fracture;
- stone geometry;
- the planned setting, repair, or recut.
A fully enclosed crystal and an open feather of the same visual “intensity” are not the same mechanical situation.
[VISUAL 47.2: Three separate axes—clarity grade, transparency, and durability—with examples in which they do not move together]
Surface Relationship and the 2D–3D Problem
A plot can show approximate position but not necessarily the depth of a characteristic. A feature plotted near the girdle may actually be deep within the stone, immediately below the surface, or open at the edge.
This is a critical distinction for work on jewelry. A professional examination should rotate the stone, use multiple lighting directions, and track the characteristic through different facets. In a mounted stone, metal may conceal part of the area.
Mounted Diamond and Examination Limitations
A setting may:
- conceal a chip, natural, or open fracture;
- prevent weighing;
- limit the view through the pavilion;
- produce reflections that resemble internal characteristics;
- make it difficult to distinguish old from new damage.
Findings on a mounted stone must therefore be described with an appropriate confidence level.
The Stone’s Condition Has a Date
A grading report describes the stone in the condition in which it was examined. Afterward, it may acquire:
- chips;
- abrasions;
- new surface damage;
- changes after repolishing or recutting;
- changes to the inscription;
- new effects from setting or repair.
An old report is therefore not a guarantee of the stone’s present physical condition.
Natural Origin, Treatment, and Clarity Are Separate Axes
Natural and laboratory-grown diamonds may have crystals, pinpoints, clouds, graining, or other clarity characteristics. Fracture filling may alter the appearance of a fracture without changing the fact that it existed. A growth remnant may be important to laboratory identification, but a clarity term alone is insufficient to determine origin.
Clarity describes characteristics. Origin requires a separate body of evidence.
How to Compare a Plot and a Stone Professionally
A practical sequence is:
- confirm the report number, weight, shape, and dimensions;
- examine the clean stone in multiple orientations;
- locate the principal plotted characteristics;
- distinguish the actual characteristic from a facet reflection;
- determine whether the characteristic is fully internal or reaches the surface;
- assess overall transparency separately;
- assess mechanically relevant characteristics separately;
- record possible changes relative to the document;
- do not draw an ownership or provenance conclusion from the plot alone.
What to Do When Two Reports Differ
A difference may result from:
- different examination dates;
- a change in the stone’s condition;
- different institutions and methodologies;
- a borderline clarity case;
- a different report format;
- an administrative error;
- substitution of the stone.
The first step is not to assume fraud or a “more lenient laboratory,” but to rematch the stone to both documents through physical examination.
[VISUAL 47.3: Matching check—report → weight/dimensions → plot → microscopy → inscription → current condition]
Integrated Conclusion Before a Decision
For a purchase, setting, repair, recut, or insurance decision, answer five questions separately:
- What is the stone?—identity and material origin.
- What is visible in it?—clarity characteristics and plot.
- How does it transmit light?—transparency.
- Is there a relevant mechanical risk?—durability in the specific context.
- Do the documents correspond to the actual stone?—matching and current condition.
A single clarity grade cannot substitute for these five answers.
Chapter Summary
- A plot is a selected 2D representation, not 3D tomography.
- Symbols are not necessarily drawn to scale.
- Inclusion, blemish, and finish are not the same category.
- Clarity is assessed by integrating five factors, not by adding points.
- A grade-setting characteristic is not necessarily the most useful one for identification.
- A plot may be a strong identification fingerprint, but it is not proof of ownership.
- Not every existing characteristic must be shown on a plot.
- Clarity grade and transparency are not the same.
- Eye-clean is not a universal laboratory grade.
- Clarity grade is not a durability score.
- Openness to the surface and 3D position must be checked on the stone.
- A report describes the condition at the time of examination and must be physically matched to the current stone.
[VISUAL 47.4: Integrated examination—identity | clarity/plot | transparency | durability | documentation]