Gems by Facetability
Gems grouped by brittleness/facetability
Facetability refers to how easily a gemstone can be cut and polished into faceted shapes. It's determined by brittleness, cleavage, and internal structure. Gems with excellent facetability are easier to cut, while those with extreme cleavage or brittleness require expert handling.
Excellent Facetability (22 gems)
| Gem Type | Hardness | Mineral Group |
|---|---|---|
| Diamond | 10 | Carbon |
| Black Diamond | 10 | Carbon |
| Pink Diamond | 10 | Carbon |
| Yellow Diamond | 10 | Carbon |
| Brown Diamond | 10 | Carbon |
| Green Diamond | 10 | Carbon |
| Blue Diamond | 10 | Carbon |
| Ruby | 9 | Corundum Group |
| Sapphire | 9 | Corundum Group |
| Synthetic Sapphire | 9 | Synthetic |
| Synthetic Ruby | 9 | Synthetic |
| Alexandrite | 8.5 | Chrysoberyl Group |
| Chrysoberyl | 8.5 | Chrysoberyl Group |
| Taaffeite | 8-8.5 | Spinel Group |
| Red Spinel | 8 | Spinel Group |
| Blue Spinel | 8 | Spinel Group |
| Pink Spinel | 8 | Spinel Group |
| Burmese Spinel | 8 | Spinel Group |
| Tanzanian Spinel | 8 | Spinel Group |
| Vietnamese Purple Spinel | 8 | Spinel Group |
| Spinel | 8 | Spinel Group |
| Mahenge Spinel | 8 | Spinel Group |
Some directional weakness (36 gems)
| Gem Type | Hardness | Mineral Group |
|---|---|---|
| Phenakite | 7.5-8 | Beryllium Group |
| Paraiba Tourmaline | 7-7.5 | Tourmaline Group |
| Tsavorite | 7-7.5 | Garnet Group |
| Rubellite | 7-7.5 | Tourmaline Group |
| Indicolite | 7-7.5 | Tourmaline Group |
| Watermelon Tourmaline | 7-7.5 | Tourmaline Group |
| Rhodolite | 7-7.5 | Garnet Group |
| Almandine | 7-7.5 | Garnet Group |
| Pyrope | 7-7.5 | Garnet Group |
| Spessartite | 7-7.5 | Garnet Group |
| Grossular | 7-7.5 | Garnet Group |
| Uvarovite | 7-7.5 | Garnet Group |
| Mali Garnet | 7-7.5 | Garnet Group |
| Color-Change Garnet | 7-7.5 | Garnet Group |
| Verdelite | 7-7.5 | Tourmaline Group |
| Tourmaline | 7-7.5 | Tourmaline Group |
| Malaya Garnet | 7-7.5 | Garnet Group |
| Achroite | 7-7.5 | Tourmaline Group |
| Elbaite | 7-7.5 | Tourmaline Group |
| Andradite | 6.5-7.5 | Garnet Group |
| Amethyst | 7 | Quartz Group |
| Citrine | 7 | Quartz Group |
| Rose Quartz | 7 | Quartz Group |
| Smoky Quartz | 7 | Quartz Group |
| Ametrine | 7 | Quartz Group |
| Prasiolite | 7 | Quartz Group |
| Milky Quartz | 7 | Quartz Group |
| Rock Crystal | 7 | Quartz Group |
| Rutilated Quartz | 7 | Quartz Group |
| Tourmalinated Quartz | 7 | Quartz Group |
| Zircon | 6.5-7.5 | Zircon Group |
| Quartz | 7 | Quartz Group |
| Garnet | 6.5-7.5 | Garnet Group |
| Demantoid | 6.5-7 | Garnet Group |
| Clinohumite | 6.5-7 | Humite Group |
| Chondrodite | 6-6.5 | Humite Group |
Orientation critical (33 gems)
| Gem Type | Hardness | Mineral Group |
|---|---|---|
| Padparadscha Sapphire | 9 | Corundum Group |
| Synthetic Emerald | 9 | Synthetic |
| Musgravite | 8-8.5 | Spinel Group |
| Emerald | 8 | Beryl Group |
| Painite | 8 | Borate Group |
| Imperial Topaz | 8 | Topaz Group |
| Pink Topaz | 8 | Topaz Group |
| Aquamarine | 8 | Beryl Group |
| Morganite | 8 | Beryl Group |
| Heliodor | 8 | Beryl Group |
| Goshenite | 8 | Beryl Group |
| Green Beryl | 8 | Beryl Group |
| Topaz | 8 | Topaz Group |
| Pezzottaite | 8 | Beryl Group |
| Blue Topaz | 8 | Topaz Group |
| Opaque Emerald | 8 | Beryl Group |
| Beryl | 8 | Beryl Group |
| Bixbite | 7.5–8 | Beryl Group |
| Grandidierite | 7.5 | Borosilicate Group |
| Andalusite | 7.5 | Andalusite Group |
| Euclase | 7.5 | Beryllium Group |
| Iolite | 7-7.5 | Cordierite Group |
| Jeremejevite | 6.5-7.5 | Borosilicate Group |
| Sillimanite | 6.5-7.5 | Silicate Group |
| Serendibite | 6.5-7 | Borosilicate Group |
| Hiddenite | 6.5-7 | Spodumene Group |
| Diaspore | 6.5-7 | Oxide Group |
| Kunzite | 6.5-7 | Spodumene Group |
| Peridot | 6.5-7 | Olivine Group |
| Spodumene | 6.5-7 | Spodumene Group |
| Tanzanite | 6-7 | Zoisite Group |
| Zoisite | 6-7 | Zoisite Group |
| Kyanite | 4-7 (variable) | Kyanite Group |
Fragile during setting (34 gems)
| Gem Type | Hardness | Mineral Group |
|---|---|---|
| Hambergite | 7.5 | Borate Group |
| Danburite | 7-7.5 | Danburite Group |
| Kornerupine | 6.5-7 | Kornerupine Group |
| Axinite | 6.5-7 | Borosilicate Group |
| Vesuvianite | 6.5 | Sorosilicate Group |
| Epidote | 6-7 | Sorosilicate Group |
| Idocrase | 6.5 | Sorosilicate Group |
| Benitoite | 6-6.5 | Cyclosilicate Group |
| Moonstone | 6-6.5 | Feldspar Group |
| Labradorite | 6-6.5 | Feldspar Group |
| Sunstone | 6-6.5 | Feldspar Group |
| Amazonite | 6-6.5 | Feldspar Group |
| Orthoclase | 6-6.5 | Feldspar Group |
| Andesine | 6-6.5 | Feldspar Group |
| Oligoclase | 6-6.5 | Feldspar Group |
| Prehnite | 6-6.5 | Phyllosilicate Group |
| Feldspar | 6-6.5 | Feldspar Group |
| Bytownite | 6-6.5 | Feldspar Group |
| Petalite | 6-6.5 | Phyllosilicate Group |
| Albite | 6-6.5 | Feldspar Group |
| Sodalite | 5.5-6 | Feldspathoid Group |
| Scapolite | 5.5-6 | Scapolite Group |
| Diopside | 5.5-6 | Pyroxene Group |
| Hackmanite | 5.5-6 | Sodalite Group |
| Hauyne | 5.5-6 | Sodalite Group |
| Opaque Hauyne | 5.5-6 | Sodalite Group |
| Amblygonite | 5.5-6 | Phosphate Group |
| Vayrynenite | 5.5 | Phosphate Group |
| Afghanite | 5.5 | Cancrinite Group |
| Enstatite | 5-6 | Pyroxene Group |
| Hypersthene | 5-6 | Pyroxene Group |
| Brazilianite | 5.5 | Phosphate Group |
| Pargasite | 5-6 | Amphibole Group |
| Apatite | 5 | Phosphate Group |
Extreme cleavage (27 gems)
| Gem Type | Hardness | Mineral Group |
|---|---|---|
| Sapphirine | 7.5 | Sapphirine Group |
| Pollucite | 6.5-7 | Zeolite Group |
| Cassiterite | 6-7 | Oxide Group |
| Tantalite | 6-6.5 | Tantalite Group |
| Triplite | 5-6 | Triphalosilicate Group |
| Sphene | 5-5.5 | Titanite Group |
| Chrome Sphene | 5-5.5 | Titanite Group |
| Herderite | 5-5.5 | Phosphate Group |
| Stibiotantalite | 5-5.5 | Tantalate Group |
| Poudretteite | 5 | Osumilite Group |
| Dioptase | 5 | Cyclosilicate Group |
| Scheelite | 4.5-5 | Tungstate Group |
| Xenotime | 4-5 | Phosphate Group |
| Parisite | 4.5 | Rare Earth Carbonate Group |
| Bastnasite | 4-4.5 | Carbonate Group |
| Smithsonite | 4-4.5 | Carbonate Group |
| Rhodochrosite | 3.5-4.5 | Carbonate Group |
| Fluorite | 4 | Halide Group |
| Sphalerite | 3.5-4 | Sulfide Group |
| Malachite | 3.5-4 | Carbonate Group |
| Azurite | 3.5-4 | Carbonate Group |
| Aragonite | 3.5-4 | Carbonate Group |
| Cuprite | 3.5-4 | Oxide Group |
| Cerussite | 3-3.5 | Carbonate Group |
| Phosphophyllite | 3-3.5 | Phosphate Group |
| Calcite | 3 | Carbonate Group |
| Erythrite | 1.5-2.5 | Arsenate Group |
Cabochon Preferred (37 gems)
| Gem Type | Hardness | Mineral Group |
|---|---|---|
| Star Sapphire | 9 | Corundum Group |
| Star Ruby | 9 | Corundum Group |
| Cat's Eye Chrysoberyl | 8.5 | Chrysoberyl Group |
| Aventurine | 7 | Quartz Group |
| Tiger's Eye | 7 | Quartz Group |
| Hawk's Eye | 7 | Quartz Group |
| Chalcedony | 7 | Quartz Group |
| Agate | 7 | Quartz Group |
| Carnelian | 7 | Quartz Group |
| Chrysoprase | 7 | Quartz Group |
| Onyx | 7 | Quartz Group |
| Sardonyx | 7 | Quartz Group |
| Bloodstone | 7 | Quartz Group |
| Jasper | 7 | Quartz Group |
| Jadeite | 6.5-7 | Pyroxene Group |
| Nephrite | 6-6.5 | Amphibole Group |
| Black Opal | 5.5-6.5 | Opal Group |
| Fire Opal | 5.5-6.5 | Opal Group |
| Crystal Opal | 5.5-6.5 | Opal Group |
| Boulder Opal | 5.5-6.5 | Opal Group |
| White Opal | 5.5-6.5 | Opal Group |
| Jelly Opal | 5.5-6.5 | Opal Group |
| Hyalite | 5.5-6.5 | Opal Group |
| Peruvian Opal | 5.5-6.5 | Opal Group |
| Sugilite | 5.5-6.5 | Sugilite Group |
| Rhodonite | 5.5-6.5 | Pyroxenoid Group |
| Opal | 5.5-6.5 | Opal Group |
| Hematite | 5.5-6.5 | Oxide Group |
| Charoite | 5-6 | Charoite Group |
| Lapis Lazuli | 5-6 | Lazurite Group |
| Turquoise | 5-6 | Phosphate Group |
| Moldavite | 5-6 | Tektite Group |
| Larimar | 4.5-5 | Pectolite Group |
| Serpentine | 2.5-5.5 | Serpentine Group |
| Seraphinite | 2-4 | Clinochlore Group |
| Ammolite | 1-3 | Other Organic Minerals |
| Lepidolite | 1-3 | Other Organic Minerals |
Unassigned (13 gems)
| Gem Type | Hardness | Mineral Group |
|---|---|---|
| Synthetic Moissanite | 9.25 | Synthetic |
| Color Change Sapphire | 9 | Corundum Group |
| Rhodizite | 8.5 | Borate Group |
| Chrome Tourmaline | 7-7.5 | Tourmaline Group |
| Color Change Garnet | 7-7.5 | Garnet Group |
| Hessonite | 6.5-7.5 | Garnet Group |
| Hydrogrossular | 6.5-7 | Garnet Group |
| Sinhalite | 6.5-7 | Borate Group |
| Fire Agate | 6.5-7 | Quartz Group |
| Mawsitsit | 6-7 | Jadeite Group |
| Hemimorphite | 4.5-5 | Silicate Group |
| Brucite | 2.5-3 | Other Minerals |
| Amber | 2-2.5 | Organic Gem |