What is a diamond plot on a grading certificate?
By Jared James · Last updated 21 May 2026
Definition
A plot is a diagram of a gemstone's clarity characteristics, showing the position and type of every inclusion and blemish that the gemologist found when grading the stone. On a GIA certificate, for example, the plot uses standard symbols to mark different clarity features, with inclusions shown in red and surface blemishes in green, mapped onto a simplified drawing of the stone's top and side views. Reading the plot helps you see exactly where imperfections sit and whether they fall in a visible or less important part of the stone.
Frequently asked questions
- How do you read a diamond plot?
- The plot uses standard symbols for different types of clarity features: a dot for a pinpoint, a circle for a crystal inclusion, a line for a feather, and so on. Inclusions inside the stone are drawn in red, surface blemishes in green, and their position on the diagram reflects where they are on the actual diamond.
- Does every diamond certificate include a plot?
- Full GIA reports include a detailed plot, while smaller GIA dossier certificates do not. Other labs like IGI and AGS also include plots on most reports. For very small diamonds, a plot is often omitted as the inclusions are too tiny to map usefully.
- Can a plot help me choose a diamond?
- Yes, especially for checking whether a large inclusion sits directly under the table facet, which is where it will be most visible, or off to the side where a claw can hide it. Two diamonds with the same clarity grade can look very different depending on where their inclusions fall.
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