These are applied to gemstones to help enhance their brilliance.
The small, flat surfaces on the external faces of a gem are referred to as facets. When you hear someone refer to the cut of the gem, it simply means how well the facets are symmetrically balanced or how close they are to well-known standard profiles. Facets are applied to the table, crown, and pavilion of a gem and sometimes are even cut onto the girdle (the widest part of a gem).
The Tolkowsky round brilliant cut design is a cut that was carefully calculated by Marcel Tolkowsky in 1919. It has 57 facets, where all of their angles are precisely detailed, so as to maximise the brilliance and lustre of a Diamond.
On a brilliant cut gemstone, the shape of the facets are normally triangular and kite-like in appearance. On octogon and emerald cut gemstones the facets tend to be rectangular in shape. The bigger the quantity of facets applied to the crown, the higher the chance of scintillation: however, if too many facets are applied to the crown then the amount of internal brilliance seen will most likely be reduced.
Amazingly, even on a tiny 1.5mm Diamond or Topaz, often 57 miniscule facets are applied and all of the cutting is done by hand!
