| Gemstone | To scale | Specific gravity | Mohs hardness | Composition | Varieties |
|---|
| Zircon | | 4.6–4.7 | 7.5 | Zirconium silicate | Jargon, Matura diamond, Hyacinth |
| Corundum | | 3.96–4.05 | 9 | Aluminum oxide | Ruby, Sapphire |
| Garnet | | 3.5–4.3 | 6.5–7.5 | A group of silicate minerals | Almandine, Almandine-spessartine, Andradite, Demantoid, Topazolite, Grossular, Tsavorite, Hessonite, Pyrope, Chrome pyrope, Pyrope-Almadine, Pyrope-Spessartine, Malaia, Color-change garnet, Rhodolite, Spessartine, Uvarovite |
| Spinel | | 3.58–4.06 | 8 | Magnesium aluminum oxide | Balas ruby, Almandine spinel, Rubicelle, Sapphire spinel and ghanospinel, Chlorspinel |
| Chrysoberyl | | 3.68–3.78 | 8.5 | Beryllium aluminum oxide | Chrysoberyl, Alexandrite, Cat's eye |
| Topaz | | 3.5–3.6 | 8 | Aluminum silicate fluoride hydroxide | none listed |
| Diamond | | 3.51 | 10 | Carbon | none listed |
| Peridot | | 3.22–3.45 | 7 | Magnesium iron silicate | none listed |
| Jadeite | | 3.1–3.5 | 6 | Sodium aluminum silicate | none listed |
| Tourmaline | | 3.03–3.25 | 7–7.5 | Complex aluminum borosilicate | Achorite, Brazilian emerald, Dravite, Indicolite, Rubellite, Siberite, Verdilite |
| Nephrite | | 2.9–3.1 | 6 | Calcium magnesium silicate | none listed |
| Lapis lazuli | | 2.7–2.9 | 5–5.5 | A rock composed mainly of the mineral lazurite with variable amounts of pyrite (brassy flecks) and white calcite | none listed |
| Beryl | | 2.63–2.91 | 7.5–8 | Beryllium aluminum silicate | Emerald, Aquamarine, Morganite, Heliodore, Red beryl, Goshenite |
| Turquoise | | 2.6–2.8 | 5–6 | Hydrous copper aluminum phosphate | none listed |
| Feldspar | | 2.55–2.76 | 6–6.5 | Two distinctly different alkali alumino silicates: the Plagioclase and the Alkali Feldspar Series | Labradorite, Sunstone, Peristerite, Amazonite, Moonstone |
| Quartz | | 2.65 | 7 | Silicon dioxide or silica | Rock crystal, Amethyst, Citrine, Morion, Smoky quartz or cairngorm, Rose quartz, Green quartz or praziolite, Agate |
| Opal | | 1.98–2.25 | 5.5–6.5 | Hydrated silica | White opal, Black opal, Water opal, Fire opal |