Recently we got in two GIA “triple excellents”.
In case you’re wondering, a GIA triple excellent diamond is one that has three excellent grades – for cut, polish and symmetry.
One was perfect, as shown on the left, however, the other one had a light patch in the centre, as shown on the right.
So what causes that white patch in the centre?
The answer lies in the fact that the diamond on the right has a pavillion angle of 41.6 degrees. It’s still an excellent grade, however, it is important that laboratory grades are almost always ranges – not exact measurements. Therefore, if you want to have what is usually called an Ideal Cut, it is important to look beyond the laboratory grade and look at either:
- The entire set of proportions.
- An Ideal Scope image.
- Other methods such as the BrillianceScope or software ray-tracing.