Clarity Grading
Diamond clarity is not a measure of “perfection” in an absolute sense. It is a standardized evaluation of the relative presence and visibility of internal and surface features.
A diamond can have one feature that strongly affects the grade. Another can have several small features whose combined effect is less significant. Clarity is therefore not determined by simply counting dots.
Inclusions and Surface Features
In gemological terms, it is important to distinguish between:
- inclusions—internal features or features that extend into the stone;
- surface features / blemishes—irregularities confined to the surface.
The clarity grade is produced by evaluating their effect according to the rules of the system.
The word “inclusion” does not automatically mean a foreign mineral impurity. An inclusion can be a crystal, fracture, growth feature, or another internal structure.
The GIA Clarity Scale
The GIA system has eleven grades:
- FL—Flawless
- IF—Internally Flawless
- VVS1, VVS2—Very Very Slightly Included
- VS1, VS2—Very Slightly Included
- SI1, SI2—Slightly Included
- I1, I2, I3—Included
The numbers 1, 2, and 3 do not indicate the number of inclusions. They identify a position within a broader clarity category.
FL does not mean “indestructible,” and I3 is not itself a numerical measure of the probability of breakage. Clarity and durability are related only in certain cases and must be evaluated separately.
Reference Magnification of 10×
The GIA clarity grade is based on features relevant at 10× magnification under standardized conditions.
A microscope at higher magnification is useful for locating, identifying, and analyzing features, but the final clarity grade does not automatically become lower merely because something else can be found at 40× or 100×.
This is fundamental to standardization: without an agreed reference magnification, almost every diamond could be described in ever greater detail as magnification increases.
Five Principal Factors
When grading clarity, GIA considers five interconnected factors:
Size
How large is the feature relative to the stone?
Number
How many relevant features or their reflections affect the observation?
Position
Is the feature beneath the table, near the edge, at a point, or in a less conspicuous location?
Nature
What type of feature is it, and how does it relate to the stone’s structure?
Color or relief
How much visual contrast does the feature have against the surrounding diamond, including differences in color, brightness, or darkness?
No one factor is sufficient in every case.
The Grade-Setting Feature
In many diamonds, one feature or a group of related features has the greatest influence on the clarity grade.
The practical question is therefore:
What actually determined this grade?
Two VS2 diamonds can be very different:
- one because of a small darker crystal beneath the table;
- another because of several less visible feathers;
- a third because of a cloud of tiny pinpoints;
- a fourth because of a feature near the girdle.
The same designation does not mean an identical microscopic image.
A Brief Overview of Clarity Characteristics
This chapter is not intended to be an atlas of inclusions. Detailed morphology and geological significance belong to Chapters 40–47.
To read a clarity report, it is sufficient to distinguish several common terms:
- crystal—a crystalline inclusion;
- feather—a fracture that may appear feather-like because of reflection;
- cloud—a group of very small features that together create a cloud;
- pinpoint—a very small dot-like inclusion;
- twinning wisp—a group of features associated with growth/twinning;
- cavity—a depression or opening at the surface;
- knot—a crystalline inclusion that reaches the surface and may be polished together with the diamond;
- chip—a localized loss of material;
- graining—a structural growth or deformation feature that may be internal or at the surface.
The name of a feature is not, by itself, a clarity grade.
A Plot Is Not a Photograph
A clarity plot on a laboratory report is a diagram, not a photomicrograph.
Its purposes can include:
- displaying important features;
- assisting with stone identification;
- documenting the approximate position of relevant features.
A plot need not show every microscopic detail. Some features may be listed in comments, and different report types have different scopes.
A “cleaner plot” is therefore not automatic evidence of a better stone.
Eye-Clean Is Not a Laboratory Clarity Grade
The term eye-clean is a trade and practical description indicating that relevant inclusions are not visible to the unaided eye under certain conditions.
Without further definition, however, we do not know:
- from what distance;
- under what lighting;
- from which direction;
- for how long;
- whether the observer knows where to look;
- whether the stone is loose or mounted.
An SI1 can be eye-clean to one observer, while some VS2 stones may contain a feature that becomes easier to see after it has been located once.
Eye-clean should therefore not be turned into a hidden twelfth GIA clarity grade.
Clarity, Transparency, and Durability Are Three Different Questions
Clarity grade describes the relative effect of inclusions and blemishes according to grading rules.
Transparency describes how well light is transmitted through the stone without general haze or scattering.
Durability describes the resistance of a specific stone to damage in actual use.
A stone can have a relatively high clarity grade yet show reduced transparency because of diffuse clouds or graining. Another can have a lower clarity grade because of a localized, readily visible inclusion while remaining fully transparent.
Likewise, a feather does not automatically mean that a diamond will break. Risk depends on geometry, position, openness, size, relationship to the edge, and the future setting.
Shape and Size Affect Visibility
Step-cut shapes such as emerald and Asscher-style cuts have large, open optical zones that can make certain inclusions more conspicuous.
Brilliant and mixed styles create many reflections that can partly mask some features, but at times can also reflect them multiple times.
A larger diamond provides more physical space for clarity features and often requires a different practical approach to visual selection than a very small stone.
This does not change the definition of clarity grade, but it changes how a buyer experiences the result.
FL and IF Are Not the Same
In Flawless (FL), there are no inclusions or blemishes relevant to the grade visible at 10× magnification.
In Internally Flawless (IF), there are no visible inclusions, but permitted surface features may be present.
Neither expression means that the surface can never be damaged after the report is issued. Repolishing, wear, a chip, or a new scratch can change the stone’s condition.
A laboratory report describes the stone at the time of examination.
Treatments and Clarity Grading
Clarity enhancement must be separated from the natural microscopic image.
GIA may issue reports for some diamonds with permanent treatments such as laser drilling, with the treatment clearly disclosed. In contrast, GIA does not issue standard grading reports for fracture-filled diamonds because the filler is not permanent and can affect appearance and the grading result.
This is current GIA policy, not necessarily the universal policy of every laboratory.
Details of laser drilling and fracture filling belong to Chapters 58–59.
Natural and Laboratory-Grown Diamonds
Clarity features can be present in both natural and laboratory-grown diamonds, but their population distributions and typical growth contexts are not identical.
One inclusion is not a sufficient independent test of natural origin.
Factual cutoff—August 8, 2026.
For natural D–Z diamonds, GIA continues to use the classic clarity scale in the applicable natural-diamond grading reports. Since October 1, 2025, it has used the Premium/Standard Quality Assessment for D–Z laboratory-grown diamonds. Under that scheme, Premium requires a VVS or higher clarity criterion, while Standard permits a VS criterion, together with the other color and finish requirements.
An older GIA laboratory-grown document may therefore look different from a current document. The date and service name are not administrative details; they determine what the result means.
A Mounted Diamond and the Limits of Examination
A setting can conceal:
- part of the girdle;
- a surface-reaching feather;
- a chip;
- a cavity;
- a knot;
- part of the pavilion.
Dirt, oil, and reflections from metal can make examination more difficult.
Precise grading of a loose stone must therefore not be replaced automatically by an assessment of a mounted stone.
Practical Protocol for Reading Clarity
- identify the laboratory, date, and report type;
- read the clarity grade;
- examine the plot if one is present;
- read the legend and comments;
- determine which feature most strongly sets the grade;
- view the stone at 10×;
- view it without magnification;
- evaluate transparency separately;
- evaluate durability and the relationship to the setting separately;
- check treatments and the stone’s current condition;
- compare two stones of the same grade physically, not only by designation.
Chapter Summary
- Clarity describes the relative absence of inclusions and surface features.
- The GIA scale has eleven grades from FL to I3.
- The reference magnification for the GIA clarity grade is 10×.
- The five key factors are size, number, position, nature, and color or relief.
- The number of inclusions alone does not determine the grade.
- A plot is a diagram, not a photograph or complete atlas of the stone.
- Eye-clean is a trade description, not a laboratory clarity grade.
- Clarity, transparency, and durability must be distinguished.
- GIA does not issue grading reports for fracture-filled diamonds, while some more stable treatments may be reported with disclosure.
- The current GIA D–Z laboratory-grown Quality Assessment does not present clarity in the same way as the classic natural-diamond report.
[VISUAL 28.1: GIA clarity scale—FL, IF, VVS, VS, SI, and I]
[VISUAL 28.2: Five clarity-grading factors—size, number, position, nature, and color or relief]
[VISUAL 28.3: Plot versus an actual 3D inclusion—why a diagram is not a photograph]
[VISUAL 28.4: Clarity versus transparency versus durability—three separate axes]
[VISUAL 28.5: Brief atlas of clarity terms with cross-links to Chapters 40–47]