A Trilliant or Trillion cut plain and simple is a Triangular shaped diamond cut in the "brilliant cut" style.
These diamonds have many facets and refract the light beautifully
The cut was developed in Amsterdam and is produced from a radiant cut diamond, used mostly in jewelry.
The most noted use is to flank a center diamond and the reason for this is that a trillion can be cut with varied levels of brilliance.
There are two different edges you can get with a trillion; straight edged or curved edge diamonds:
Straight edged trillions can be used to make up different shaped diamonds when combined, i.e. octagons and other invisible settings, (also known as a "pizza setting").
Curved edge trillions can be used as side stones on an engagement rings, tennis bracelets, necklaces and solitaires.
The key ingredient to look for when purchasing these triangular diamonds (curved or straight edge trillions) is an even ration between the corners; the ideal is a 1:1 ratio. The reason behind this is that it is a triangular shape and the ratio of each side being exactly equal is the best way to insure that this cut of diamond will look its best.
The better the symmetry is on the stone, the better it will look in the setting. A trillion is set in V shaped prongs to protect the corners of the stone, they can also be cut for invisible settings. A Trillian is a beautiful shape that can enhance the look of your ideal design.