Diamonds are unique gemstones. However, most of them share some structural features, and one of them is the culet, which is the bottom tip or point of a diamond. A diamond can either have a pointed culet basically described as "none" on grading reports or an additional rough to the diamond's table. The culet (pronounced as cue-let) in a diamond is an additional facet to the total number of the diamond's facets. In some cases, you will find out that a brilliant-cut has 57 facets, and some 58; the 58th facet is the culet.
Generally, all diamonds have a pointed culet, representing the facets of the pavilion all joining at a sharp point at the bottom of the diamond. However, specific diamonds feature an additional facet at the culet that sits parallel to the diamond’s table.
Grading of Diamond Culet
The culet is a segment of the cut grade. During the manufacturing process, the culet is often polished as a flat facet so that it does not get chipped. Nowadays, the cutter usually closes this facet up to a certain point, and sometimes it is left as a small extra facet. Its small size is advantageous as it protects the culet from chipping when the diamond is handled, or the stone is being set.
There are different grading scales for diamond color, carat, and cut. The most popular grading standard is the GIA (Gemological Institute of America). On the GIA scale, the culet is described based on its size. The grades used include:
- very small - A diamond with a culet of less than 1.5% of its average diameter is graded as having a Very Small culet.
- small- A diamond with a culet of around1.5% of its average diameter is graded as having a Small culet.
- medium - A diamond with a culet of around 3% of its average diameter is graded as having a Medium culet.
- slightly large - A diamond with a culet of approximately 5% of its average diameter is graded as having a Slightly Large culet. A culet of this size is often visible to the naked eye in a mid-sized or large diamond.
- Large - A diamond with a culet of approximately 7% of its average diameter is graded as having a Large culet. A culet of this size is usually visible to the naked eye in a mid-sized diamond.
- Very Large - A diamond with a culet of approximately 11% of its average diameter is graded as having a Very Large culet. A Very Large culet will be easy to see when the diamond is viewed from above.
Extremely Large - A diamond with a culet of 15% or more of its average diameter is graded as having an Extremely Large culet. An Extremely Large culet is very easy to see from the table of the diamond.
Initially, the culet was added to a diamond to cover the stone. Although a diamond is very tough, the pointed tip at the bottom of a diamond can potentially break if the stone is hit with an immense amount of force.
These days, most diamonds don’t have an extra facet at the culet. Since a considerable culet can negatively impact the formation of a diamond, it’s best to stick to diamonds that have no culet. This is usually referred to as a pointed culet, as the bottom of the diamond has a point rather than a flat texture. Here, Large and Slight large may affect the appearance of the diamond.
Impact of Culets on a Diamond
The main benefit of the culet is that it protects the diamond bottom from chipping. Its detriment is a flat facet that is parallel to the table such that you can see through the diamond from the top via the culet. The bigger the culet, the more you can see through the diamond. However, its large size makes the diamond look like it has discoloration or a large inclusion.
The Culet size is always noted on the diamond's certificate, that is, if the diamond is certified. Therefore, as long as the culet is proportional and symmetrical with the diamond, it does not hurt the diamond in any way.