Beryl

Beryl is a mineral composed of beryllium aluminium cyclosilicate with the chemical formula Be₃Al₂Si₆O₁₈. Well-known varieties of beryl include emerald and aquamarine. Naturally occurring, hexagonal crystals of beryl can be up to several meters in size, but terminated crystals are relatively rare.

Top values go to clarity first, with color a close second. Since beryls are available in large sizes, there is usually no incremental price increase for large beryls. All beryls hold the same value above about three carats. (Red beryl is an exception).

Emerald: very strong bluish green to green, tone 3 to 8, saturation 2 to 5. Top color: vstbG 5/5; bG 5/5 or 6/5; vslbG 5/5
Green beryl: slyG 4/3
Morganite: slpR 3/4
Heliodor: Y 4/4