has three main components: Hue, Tone and
is described as the shade, tint or sensation
of a color. The GIA GemSetŪ has 31 Hues
which can be used to describe viturally
all colored gemstones. The complete GIA
GemSetŪ has 324 sample hue colors with varying
Tones and Saturations.
is described as the relative lightness or
darkness of a Hue. The GIA Tone Scale is
divided into 11 grades, 0 to 10, with 0
being colorless to 10 being black.
is described as the strength or purity of
a Hue. The GIA Saturation Scale is from
1 to 6. The lower numbers (1, 2 or 3) of
warm colors such as red, orange or yellow
tend to look brownish and the cool colors
such as blue and green tend to look grayish.
Level 4 no longer shows either grayishness
or brownishness, while neither is strong
or weak. Level 5 is strong and level 6 being
vivid, almost over colored.