Introduction
A GIA grading report assigns every diamond a clarity grade — a single designation from Flawless to I3. But the grade is a summary. The plot is the evidence.
The clarity plot is a pair of diagrams on every GIA report: one showing the diamond from above (crown view), another from below (pavilion view). Together, they map the location, type, and category of every characteristic the grader identified. If the clarity grade tells you how clean a diamond is, the plot tells you why — and where to look to verify it yourself.
For Czech consumers evaluating diamonds online or comparing stones at a jeweller, the plot is the most informative section of the report. This article explains how to read it — symbol by symbol, comment by comment.
Key Points
Crown and Pavilion Views
The GIA plot uses two outline diagrams of the diamond's facet structure:
- Crown view (top-down) — characteristics as seen looking down through the table facet. This is the viewing angle that matters most, because it represents how you see the diamond when mounted.
- Pavilion view (bottom-up) — characteristics from beneath the stone. Features plotted here may be deep within the diamond and invisible from the crown.
A single inclusion can appear on both views if it spans from crown through to pavilion. Comparing the two gives you a sense of where the characteristic sits in three-dimensional space — critical for judging whether it is likely to be visible during wear.
Colour Coding: Red and Green
- Red symbols mark inclusions — characteristics entirely internal to the diamond. Crystals, needles, contained feathers, clouds, pinpoints, twinning wisps. Permanent features that cannot be removed without re-cutting.
- Green symbols mark blemishes — characteristics on or reaching the polished surface. Scratches, nicks, naturals, knots, cavities, surface-reaching feathers.
A plot dominated by red tells you the grade is driven by the diamond's internal structure. Green-dominated plots suggest surface features, some of which could theoretically be improved through re-polishing (see Inclusions vs Blemishes).
The Symbol Legend
GIA uses standardised symbols. The most common:
| Symbol | Characteristic | Colour | What it is |
|---|---|---|---|
| Small dot | Pinpoint | Red | Microscopic included crystal |
| Line or rod | Needle | Red | Long, thin included crystal |
| Branching line | Feather | Red or Green | Internal fracture (red if contained; green if surface-reaching) |
| Shaded area | Cloud | Red | Cluster of pinpoints appearing hazy |
| Irregular ribbon | Twinning wisp | Red | Complex formation along a twin plane |
| Solid shape | Crystal | Red | Trapped mineral, transparent or dark |
| Small opening | Cavity | Green | Void from a dislodged near-surface inclusion |
| Bump symbol | Knot | Green | Included crystal extending to the surface |
| Textured girdle area | Natural | Green | Remnant of original rough crystal surface |
Many diamonds in the VS range and above show only two or three symbol types. For detailed descriptions of each, see Clarity Characteristics.
Reading the Plot Step by Step
1. Note the clarity grade. It sets your expectations for severity before you interpret symbols.
2. Start with the crown view. Characteristics under or near the table are most likely visible. Those near the girdle are often hidden by the setting.
3. Check the dominant colour. Red-dominated means inclusions drive the grade. Green-dominated means surface features are more prominent (see Clarity Grading Factors).
4. Find the grade-setting characteristic. Typically the largest or most central symbol — the one that most influenced the grader's decision. Identify its type and position.
5. Cross-reference the pavilion view. A crystal deep in the pavilion can create reflections visible from the crown. Characteristics near the culet may be reflected multiple times by pavilion facets, amplifying their visual impact.
6. Read the comments section. Always. The plot cannot convey everything.
The Comments Section
Below the plot on every GIA report is a comments section — essential context that the diagram cannot represent. Key phrases to understand:
"Additional clouds are not shown." The diamond contains diffuse cloudiness too widespread to mark with discrete symbols. Common on SI and I grades. Does not automatically mean haziness, but warrants visual inspection.
"Clarity grade is based on clouds that are not shown." More serious. The grade-setting characteristic is a cloud formation the plot cannot represent. Such diamonds range from eye-clean to noticeably milky — the grade alone does not distinguish. Request photographs or video. See Clarity-Transparency Bridge for how pervasive clouds affect transparency.
"Pinpoints are not shown." Scattered pinpoints too numerous to plot individually. Typically less concerning than unplotted clouds.
"Surface graining is not shown." Crystal lattice distortion visible as faint lines under magnification. The diamond may show subtle patterns the diagram does not reflect.
What the Plot Does Not Tell You
The plot is a map, not a photograph. Key absences:
- Relief. Whether an inclusion is dark, white, or transparent. The same red crystal symbol could mark a nearly invisible colourless diamond crystal or a conspicuous dark garnet.
- Size precision. Symbols show position and type, not proportional size.
- Visual impact in motion. A characteristic prominent on the static diagram may be masked by brilliance during normal viewing — or may flash conspicuously.
- Cumulative haze. Widespread cloudiness and diffuse pinpoints affect transparency but cannot be conveyed through individual symbols. This is why the comments section exists.
Tips for Czech Consumers
- Request high-resolution report scans. Czech consumer protection entitles you to full product documentation.
- Compare plot to photographs. Locate the grade-setting inclusion in the seller's images using the plot. If you cannot find it, the stone may be cleaner than the grade suggests.
- Watch for "not shown" comments. Especially regarding clouds — ask the seller about transparency.
- Position over quantity. A single crystal under the table matters more than five pinpoints near the girdle.
Summary
The GIA clarity plot maps every graded characteristic by type, category, and position. Combined with the comments section — which captures what the diagram cannot show — it gives you a complete picture of why a diamond received its clarity grade. The grade tells you where a diamond sits on the scale. The plot tells you what that grade means for this specific stone. For any significant diamond purchase, reading the plot is the difference between buying a grade and buying a diamond.
All terminology follows GIA (Gemological Institute of America) grading standards. For the clarity scale, see GIA Clarity Scale. For individual characteristic types, see Clarity Characteristics. For grading criteria, see Clarity Grading Factors.