Guide to Hardness, Refractive Index and Density

Gemstone Name
Hardness
Refractive Index
Density
Agate
6.5-7
1.53
2.61
Alexandrite
8.5
1.740-1.770
3.68-3.801
Amber
2-3
1.54
1.05-1.10
Amethyst
7
1.544-1.553
2.651
Ametrine
7
1.544-1.553
2.651
Apatite
5
1.630-1.645
3.10-3.35
Aquamarine
7.5-8
1.567-1.590
2.66-2.88
Beryl
7.5
1.560-1.602
2.62-2.90
Chalcedony
6.5-7
1.53 or 1.54
2.58-2.64
Chrome Diopside
5.5-6
1.671-1.702
3.17-3.32
Chrysoberyl
8.5
1.75 or 1.76
3.7-3.72
Chrysoprase
6.5-7
1.525-1.545
2.651-2.91
Citrine
7
1.544-1.533
2.651
Coral
2.5-4
1.49-1.65
2.60-2.72
Diamond
10
2.418
3.52
Emerald
7.5-8
1.571-1590
2.68-2.78
Garnet
6.5-7.5
1.880-1.895
3.4-4.3
Iolite
7-7.5
1.53 or 1.54
2.53-2.65
Jade
6.57
1.655-1.67
-
Kunzite
6.5-7
1.654-1.679
-
Lapis
5-6
1.50
2.38-2.42
Moonstone
6-6.5
1.52
-
Opal
5-6.5
1.42-1.47
-
Pearl
2.5-4.5
1.53-1.69
2.68-2.74
Peridot
6.5-7
1.640-1690
3.20-345
Quartz
7
1.544-1.553
2.651
Ruby
9
1.76 or 1.77
3.99-4.1
Sapphire
9
1.76 or 1.77
3.99-4.1
Spinel
7.5-8
1.715-1.747
3.55-3.63
Tanzanite
6.5
1.691-1.700
3.11-3.40
Topaz
8
1.607-1.649
3.50-3.57
Tourmaline
7
1.62-1.64
3.02-3.26
Turquoise
5-6
1.61-1.65
2.65-2.90
Zircon
6.5-7
1.78-2.01
4.00-4.80

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