- Important gemstones
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▪ TableImportant gemstonesmineral gem name colour Mohs hardness* specific gravity*beryl aquamarine sky blue to greenish blue 7½–8 2.68–2.71emerald green 2.68–2.74goshenite colourless; greenish yellow, yellow green, brownish same as aquamarineheliodor golden yellow same as aquamarinemorganite pink 2.80–2.90chrysoberyl alexandrite; also cymophane; cat's-eye green in daylight, red in incandescent light 8½ 3.6–3.8corundum padmaradschah orange 9 4.0–4.1ruby redsapphire blue; variable other than reddiamond colourless to faint yellowish tinge; also variable 10 3.52potashfeldspar orthoclase pale yellow; flesh red 6 2.6moonstone colourless; also white to yellowish, and reddish to bluish grayamazonite (amazon-stone) yellow green to blue greenplagioclase peristerite pastel pink to gray 6–6½ 2.6–2.7sunstone (aventurine) colourless with reddish glow provided by inclusionslabradorite grayishalmandine carbuncle deep red with a trace of purple 7½ 4.3andradite demantoid; Uralian emerald deep emerald-green 6½ 3.9grossularite hessonite; South African jade brownish yellow or orange to orange, red, or green 7¼ 3.6pyrope dark blood red 7–7½ 3.6spessartite yellowish orange; brownish to orange red 7¼ 4.2jadeite Imperial jade pure white to black, red, brown, yellow, blue, mauve, various greens 6 3.2–3.4nephrite mutton-fat jade deep spinach green to near-white 5–6 3.0–3.4lazurite lapis; lapis lazuli deep blue, azure blue, greenish blue 5–5½ 2.4–2.95(bluish coloured with flecks of white and gold) (5½) (2.7–2.9)olivine peridot; chrysolite yellow green; dark bottle green; olive green 6½–7 3.3–3.5quartz amethyst purple 7 2.65cairngorm; smoky quartz smoky gray to browncitrine yellowrock crystal colourlessrose quartz pinkagate (moss agate, mocha stone) variablechalcedony (onyx carnelian, sard, sardonyx, prase, chrysoprase, plasma, bloodstone, heliotrope) variablejasper variablecristobalite opal white to colourless; milky to bluish white; variable pale shades 7 2.0–2.3spinel Balas ruby rubicelle almandine red; also variable 8 3.6topaz wine yellow; pale blue, green, violet, or red 8 3.5–3.6tourmaline achroite colourless 7–7½ 3.0–3.2Brazilian emerald greendravite brownindicolite dark bluerubellite pinksiberite violetturquoise sky blue; greenish blue 6 2.6–2.8zircon jargon variable 7½ 4.6–4.7Matura diamond colourlesshyacinth (jacinth) yellow, orange, red, brownmineral gem name refractive indices dispersion* transparency crystal system habit remarksberyl aquamarine epsilon = 1.570–1.580omega = 1.574–1.586d = 0.014 transparent hexagonal large, often flawless, crystals with complex terminationsemerald epsilon = 1.571–1.581omega = 1.577–1.588 simple hexagonal crystals terminated by a flat face; often contains inclusionsgoshenite same as aquamarineheliodor same as aquamarinemorganite epsilon = 1.580–1.590omega = 1.589–1.601chrysoberyl alexandrite; also cymophane; cat's-eye alpha = 1.746beta = 1.748gamma = 1.756d = 0.015 transparent orthorhombic flattened crystals often twinned chrysoberyl cat's-eye is chatoyantcorundum padmaradschah epsilon = 1.757–1.768omega = 1.765–1.776d = 0.018 transparent hexagonalruby flat-terminated crystals fluoresces in ultraviolet light; marked dichroismsapphire pointed dipyramids marked diochroismdiamond n = 2.4175d = 0.063 transparent isometric flattened octahedrons; dodecahedrons perfect cleavage parallel to octahedron face; sometimes fluorescent in long-wave ultraviolet lightpotashfeldspar orthoclase alpha = 1.518beta = 1.522gamma = 1.522 transparent to opaque monoclinic crystals two excellent cleavages at right anglesmoonstone same as orthoclase nodules; masses blue opalecsence; schilleramazonite (amazon-stone) alpha = 1.514beta = 1.518gamma = 1.521 triclinic large crystals variety of microclineplagioclase peristerite alpha = 1.527–1.577beta = 1.531–1.585gamma = 1.538–1.590 transparent to opaque triclinic prismatic crystals iridescentsunstone (aventurine) spangled appearancelabradorite compact masses brilliantly iridescent over large areasalmandine carbuncle n = 1.830d = 0.024 transparent (for light-coloured varieties) to opaque isometric euhedral crystals, with dodecahedrons and trapezohedrons most commonandradite demantoid; Uralian emerald n = 1.887d = 0.057grossularite hessonite; South African jade n = 1.734d = 0.028pyrope n = 1.714d = 0.027spessartite n = 1.800jadeite Imperial jade alpha = 1.640–1.658beta = 1.645–1.663gamma = 1.652–1.673 translucent to opaque monoclinic compact or fibrous massesnephrite mutton-fat jade alpha = 1.600–1.672beta = 1.614–1.686gamma = 1.627–1.693 translucent to opaque monoclinic compact or fibrous masseslazurite lapis; lapis lazuli n = 1.50(opaque) isometric(compact masses) lapis lazuli is a rock containing lazurite as its colouring agent; because it is a rock, its composition and properties are variable; properties given in parentheses are for the rock, the others for the mineral lazuriteolivine peridot; chrysolite alpha = 1.635–1.671beta = 1.652–1.698gamma = 1.671–1.707d = 0.020 transparent orthorhombic flattened prismatic crystals; granular massesquartz amethyst epsilon = 1.553omega = 1.544d = 0.013 transparent hexagonalcairngorm; smoky quartz octahedral crystalscitrinerock crystalrose quartzagate (moss agate, mocha stone) translucent to opaque compact masses; nodulesjaspercristobalite opal n = 1.435–1.455 opaque tetragonal submicrocrystalline aggregates; globular or kidney-like crusts; irregular concretions contains a variable amount of water, causing the physical properties to varyspinel Balas ruby rubicelle almandine n = 1.715–1.725d = 0.020 transparent isometric octahedral crystals; rounded grains; massive fluoresces red in long-wave ultraviolet lighttopaz alpha = 1.606–1.629beta = 1.609–1.631gamma = 1.616–1.638d = 0.014 transparent orthorhombic prismatic crystalstourmaline achroite epsilon = 1.610–1.650omega = 1.635–1.675d = 0.016 transparent hexagonal prismatic crystals, often rounded or barrel-shaped; massiveBrazilian emeralddraviteindicoliterubellitesiberiteturquoise alpha = 1.61beta = 1.62gamma = 1.65 opaque triclinic cryptocrystalline to fine granular massive colour fades on contact with sunlightzircon jargon epsilon = 1.968–2.015omega = 1.923–1.960d = 0.048 transparent tetragonal square prismatic crystals; grains*Properties given here are for gem-quality material and hence may differ from those of the mineral.See as table:
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Universalium. 2010.
