1. The table of the diamond is the top of the diamond, and the optimum proportion is about 53%~58% of the diameter of the diamond. If the proportion is too large, it will affect the brilliance of the diamond.
2. Crown angle: the included angle between the crown slope and the drill waist. If the crown angle is too small, the table is too big, and if the crown angle is too big, the diamond table is too small.
3. Below: The angle between the pavilion slope and the drill waist affects the degree of refraction light source of the diamond.
4. Crown: Generally speaking, the height above the waist is 15%~ 16% of the whole diamond diameter.
5. Drill waist: In the middle part of the diamond, if the waist of the diamond is too thick, it will be ugly from the side, and if it is too thin, it will affect the wear resistance of the diamond. The optimum waist thickness is 2%~4% of the diamond diameter.
6. Pavilion: The part below the waist, too deep or too shallow, will affect the refraction of light. The optimum pavilion depth is 42% ~ 45% of the diamond diameter.
7. Pavilion tip: refers to the sharp bottom of a diamond. The diamond with moderate size of lathe tip bottom can prevent the tip bottom from being damaged before inlaying. The best sharp angle is less than 2% of the diamond diameter.
(Excerpt from: Jewelry Boutique Discussion Area)