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Saturation scale (medium dark stone)

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March 09, 2026

GIA Color descriptions for Colored Gemstones

Gemological Institute of America (GIA) suggests to describe color for colored gemstones as Hue, Tone and Saturation.

Hue Hue is described as the shade, tint or sensation of a color. The GIA has 31 Hues and the he complete GIA GemSet^® has 324 sample hue colors with varying Tones and Saturations. In addition we put RGB (Red Green Blue) and HEX codes for your reference.
Key	Code	Name	HEX	RGB
	R	red	FA0303	R:250 G:3 B:3
	oR	orangy red	EE2102	R:238 G:33 B:2
	RO/OR	red-orange or orange-red	FB3E00	R:251 G:62 B:0
	rO	reddish orange	FE6000	R:254 G:96 B:0
	O	orange	F87B00	R:254 G:96 B:0
	yO	yellowish orange	F6A400	R:246 G:164 B:0
	oY	orangy yellow	F7CD00	R:247 G:205 B:0
	Y	yellow	F8F800	R:248 G:248 B:0
	gY	greenish yellow	CEE600	R:206 G:230 B:0
	YG/GY	yellow-green or green-yellow	B0DD00	R:176 G:221 B:0
	styG	strongly yellowish green	7BCE00	R:123 G:206 B:0
	yG	yellowish green	4DC100	R:77 G:193 B:0
	slyG	slightly yellowish green	26C200	R:38 G:194 B:0
	G	green	00C000	R:0 G:192 B:0
	vslbG	very slightly bluish green	00BE26	R:0 G:190 B:38
	bG	bluish green	00BA4A	R:0 G:186 B:74
	vstbG	very strongly bluish green	00B96F	R:0 G:185 B:111
	GB/BG	green-blue or blue-green	00B893	R:0 G:184 B:147
	vstgB	very strongly greenish blue	09B4B4	R:9 G:180 B:180
	vslgB	very slightly greenish blue	0A59AA	R:10 G:89 B:170
	B	blue	0916A5	R:9 G:22 B:165
	vB	violetish blue	0808A0	R:8 G:8 B:160
	bV	bluish violet	7B0AB4	R:62 G:8 B:170
	V	violet	7B0AB4	R:123 G:10 B:180
	bP	bluish purple	C70BC7	R:199 G:11 B:199
	P	purple	D40CB1	R:212 G:12 B:177
	rP	reddish purple	E90A9E	R:233 G:10 B:158
	RP/PR	red-purple or purple-red	F50E80	R:245 G:14 B:128
	stpR	strongly purplish red	F80E5C	R:248 G:14 B:92
	slpR	slightly purplish red	F20E33	R:242 G:14 B:51
	R	red	FA0303	R:250 G:3 B:3
	Pk	pink (exception)	FFDFDF	R:255 G:223 B:223
	Brn	brown (exception)	B7770D	R:183 G:119 B:13

Tone Tone 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.
Key	Scale	Code	Name	HEX	RGB
	0	c	Colorless or White	FFFFFF	R:255 G:255 B:255
	1	ex1	Extremely light	F8F8F8	R:248 G:248 B:248
	2	v1	Very light	F0F0F0	R:240 G:240 B:240
	3	l	Light	E8E8E8	R:232 G:232 B:232
	4	ml	Medium light	D6D6D6	R:214 G:214 B:214
	5	m	Medium	C5C5C5	R:197 G:197 B:197
	6	md	Medium dark	A3A3A3	R:163 G:163 B:163
	7	d	Dark	888888	R:136 G:136 B:136
	8	vd	Very dark	646464	R:100 G:100 B:100
	9	exd	Extremely dark	424242	R:66 G:66 B:66
	10	bl	Black	000000	R:0 G:0 B:0

Tone Scale

1	2	3	4	5	6	7	8	9	10

Saturation Saturation is described as the strength or purity of a Hue. The GIA Saturation Scale is from 1 to 6. The lower numbers such as 1, 2 or 3 of warm colors such as red, orange or yellow and 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.
Scale	Code	Name
1	gr(br)	grayish (brownish)
2	slgr	slightly grayish(brownish
3	vslgr	very slightly grayish(brownish)
4	mst	moderately strong
5	st	strong
6	v	vivid

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