A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W
X
Y
Z
Index
Tone:
A classification scale, ranging from Colourless to Extremely Dark, which indicates colour intensity in gemstones. Tone should be considered along with colour and saturation to help determine the quality of a coloured gemstone.
