The culet of a diamond is the tiny, pointed region at the bottom of the pavilion where the diamond's facets meet. It's the diamond's bottom point, or tip, in basic words. Most diamonds have a pointed culet, which means the pavilion's facets all meet at a sharp point at the diamond's base. Certain diamonds, on the other hand, have an extra facet at the culet that runs parallel to the diamond's table. The pavilion facets are evenly cut at the appropriate angle and meet at a perfect point in the majority of diamonds, giving no culet (sometimes called a pointed culet). The culet is a rough or polished facet formed when the pavilion facets do not meet at a point.
From None to Extremely Large, the culet is rated. When a loose diamond is sent for certification, it is examined face up to establish the size of the culet and from the side to assess the angle of the culet. A steeply angled culet is seen as an additional facet rather than a culet. Culet size can also be represented as a percentage of the diamond's diameter, ranging from roughly 1.5 percent to 15 percent, for certified diamonds with culets in the Small to Extremely Large range.
When grading a diamond, a gemologist will consider various aspects, including culet. Diamonds with a tiny culet or no culet at all are often considered to have a better cut than diamonds with a large, visible culet. Because the culet of a diamond is so tiny, a gemologist would usually grade it under 10x magnification.
The culet will be noted as one of several criteria that contribute to the diamond's cut grade when viewing a diamond with a GIA certificate. The GIA's International Diamond Grading System offers many distinct culet size grades:
None is the grade given to a diamond that lacks a culet facet. A diamond is said to have a "pointed" culet when all eight facets of its pavilion meet.
- Very small
A diamond with a Very Small culet is one with a culet that is less than 1.5 percent of its average diameter.
Small culet refers to a diamond with a culet that is less than 1.5 percent of its typical diameter.
A diamond with a Medium culet is one that has a culet that is roughly 3% of its average diameter.
- Slightly Large
Slightly Large culet refers to a diamond with a culet that is roughly 5% of its average diameter. In a mid-sized or big diamond, a culet of this size is frequently visible to the human eye.
A large culet diamond has a culet that is roughly 7% of the diamond's typical diameter. In a mid-sized diamond, a culet of this size is generally visible to the human eye.
- Very large
A diamond with a Very Large culet is one with a culet that is roughly 11% of its average diameter. When viewing the diamond from above, a Very Large culet will be seen.
- Extremely large
Extremely Large culet refers to a diamond with a culet that is 15% or larger than its typical diameter. From the diamond's table, an extremely large culet is easily seen.
All of these grades ensure that a diamond's brilliance is maximized. Because the culet is pointed, you won't be able to see it from the top of the diamond. When viewing a diamond from the top, a culet rated Medium, Slightly Large, or bigger may look as a tiny, black dot. The diamond's brilliance will be affected by a culet of this size, meaning it will not sparkle as brightly when light strikes it.