Culet (pronounced as Kullet or Kyoo-lit) is a polished facet at the bottom of a gemstone
parallel to the table. The word culet is derived from a latin word culus that
means bottom. Culet size as determined by GIA is based on following scale: None—>Very
Small —> Small —> Medium —> Slightly Large —> Large —> Very
Large. According GIA, “the culet is a polished
facet placed parallel to the table, the purpose of which is to prevent damage to
the point. In the GIA Laboratory, graders first assess culet size face-up,
looking through the table facet at 10X magnification.The size of
this facet is assigned a description from none to extremely large.If there is
no culet facet,the size is reported as none.When the
culet is at more than a slight angle to the table facet, the size is
also reported as none,as it is no longer considered a culet but an extra facet. Graders
observe the diamond in profile view to assess this angle.”
Culet size impactsthe cut of a diamond to a certain extent. It is also an important aspect when GIA grades diamonds. None or a small culet size that has no negative impact on a diamond’s appearance is the best choice. All that matters is the beauty/appearance of a diamond, and if a culet is large or very large, there maybe light passing through it that will reduce the brilliance of a diamond hence affecting the beauty and market value of that particular diamond.
If there is a large size culet in a diamond, light may pass through it straight through the crown and the facet without producing any sparkle creating a dead space inside the diamond. This dead area may reduce the significance of the diamond. Therefore, ideally a diamond should not have a culet. These days diamond cutters intentionally create a small culet while cutting a diamond in order to minimizes the chances of a diamond getting chipped.
Often the culet won’t be visible to a naked eye as long as it’s not really gross which is very rare. During the processing of a diamond, it is polished very precisely and neatly just as a facet. A round brilliant cut typically has 57 facets and the 58th facet is often considered as the culet of that diamond. A culet maybe examined with a x10 loupe, but it would be hard for an untrained eye to deduct or inspect a small culet.
In conclusion, it is recommended that avoiding a diamond with a very large culet size would be a smart choice and sticking to ones with none to medium culets would be your best bet.