Hardness and specific gravity are two of the major characteristics of gemstones.
Hardness of a gemstone is its resistance to scratching and may be described relative to a standard scale of 10 minerals known as the Mohs scale. F. Mohs, an Austrian mineralogist, developed this scale in 1822.
According to Mohs’ scale, the hardness of—
| Talc is | 1 |
| Gypsum is | 2 |
| Calcite is | 3 |
| Fluorite is | 4 |
| Apatite is | 5 |
| Feldspar is | 6 |
| Quartz is | 7 |
| Topaz is | 8 |
| Sapphire is | 9 |
| Diamond is | 10 |
Specific gravity is the number of times heavier a gemstone of any volume is than an equal volume of water; in other words, it is the ratio of the density of the gemstone to the density of water.
The 16 mineral gemstone groups listed below are highly prized for their beauty, durability, and rarity:
Beryl (hardness: 7.5-8 Mohs)
Beryllium aluminum silicate
Specific gravity: 2.63-2.91
Emerald: Intense green or bluish green