Degrees of Hardness of Gem-Stones | 5. | Kyanite (5–7), apatite, lapis lazuli | | 5½. | Enstatite, beryllonite, sphene | | 6. | Opal, moonstone, turquoise, diopside | | 6½. | Spodumene, peridot, garnet (demantoid), benitoite, idocrase, epidote, axinite, jade (nephrite) | | 7. | Iolite, quartz, tourmaline, jade (jadeite) | | 7¼. | Garnet (hessonite, pyrope) | | 7½. | Beryl, garnet (almandine), zircon, phenakite, euclase, andalusite | | 8. | Topaz, spinel | | 8½. | Chrysoberyl | | 9. | Corundum | | 10. | Diamond |
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