Amber
| Chemical Composition | C-H-O compound (fossil resin) |
| Crystal System | Amorphous |
| Fracture | Conchoidal, brittle |
| Hardness | 2-2.5 |
| Refractive Index | 1.54 |
| Specific Gravity | 1.05-1.09 |
| Lustre | Resinous |
Beryl
| Varieties | Aquamarine (light blue, dark blue, blue-green) |
| Emerald (green, green-yellow, green-blue) | |
| Goshenite (colourless) | |
| Golden beryl (yellow, yellow-green, golden-yellow) | |
| Morganite (pink to violet) | |
| Chemical Composition | Be3AI2(SiO3)6 Beryllium aluminum silicate |
| Crystal System | Hexagonal |
| Habit | Prismatic |
| Cleavage | Very difficult in one direction, rarely seen |
| Fracture | Conchoidal |
| Hardness | 7.25-7.75 |
| Optic Nature | Uniaxial Negative |
| Refractive Index | 1.577-1.583 (+ or - 0.017) |
| Birefringence | 0.005-0.009 |
| Dispersion | Low, 0.014 |
| Specific Gravity | 2.72 (+0.18, -0.05) |
| Lustre | Vitreous to resinous |
| Pleochroism | Weak to moderate |
Chrysoberyl
| Varieties | Green, yellow, brown, red |
| Alexandrite (colour change) | |
| Chemical Composition | BeAI2O4 |
| Crystal System | Orthorhombic |
| Habit | Pseudo-hexagonal twins |
| Cleavage | Weak to moderate |
| Fracture | Conchoidal to uneven |
| Hardness | 8.5 |
| Optic Nature | Biaxial Positive |
| Refractive Index | 1.74-1.75 |
| Birefringence | 0.009 |
| Dispersion | Low, 0.014 |
| Specific Gravity | 3.72 |
| Lustre | Bright vitreous |
| Pleochroism | Moderate to strong |
Corundum
| Varieties | Ruby (red) |
| Sapphire (blue, green, purple, yellow, orange, colourless) | |
| Chemical Composition | AI2O3 |
| Crystal System | Trigonal |
| Habit | Prismatic, tabular |
| Cleavage | None; twinned stones may show parting |
| Fracture | Conchoidal |
| Hardness | 9 |
| Optic Nature | Uniaxial Negative |
| Refractive Index | 1.762-1.770 (+.009,-.005) |
| Birefringence | 0.008-0.010 |
| Dispersion | Low, 0.018 |
| Specific Gravity | 3.99 |
| Lustre | Vitreous to Sub adamantine |
| Pleochroism | Weak to moderate |
Fluorite
| Chemical Composition | CaF2 Calcium fluoride |
| Crystal System | Cubic |
| Habit | Octahedral, cubes, interpenetrant twins |
| Cleavage | Perfect, octahedral |
| Hardness | 4 |
| Optic Nature | Isotropic |
| Refractive Index | 1.434 |
| Birefringence | Isotropic |
| Dispersion | Very low, 0.007 |
| Specific Gravity | 3.18 |
| Lustre | Poor citreous |
| Fluorescence | Bluish-white, purple (LW) |
Garnet
| Chemical Composition | X3Y2(SiO4)3 |
| X site is divalent (+2) and can be: ferrous iron, calcium, manganese, magnesium. Y site is trivalent (+3) and can be: ferric iron, aluminum, chromium, titanium. |
|
| Crystal System | Cubic |
| Habit | Dodecahedra |
| Cleavage | None |
| Hardness | 6.5-8.0 |
| Optic Nature | Isotropic |
| Refractive Index | 1.73-1.89 |
| Birefringence | None |
| Specific Gravity | 3.40-4.18 |
| Lustre | Vitreous to sub-adamantine |
Jadeite Jade
| Varieties | Green, lilac, white, pink, brown, red, blue, black, orange, yellow. |
| Chemical Composition | NaAl(SiO3)2 |
| Crystal System | Monoclinic |
| Habit | Polycrystalline |
| Fracture | Splintery |
| Hardness | 6.5-7 |
| Specific Gravity | 3.30-3.37 |
| Lustre | Greasy to vitreous |
Lapis Lazuli
| Chemical Composition | Lazurite, hauyne, calcite and pyrite |
| Habit | Aggregate |
| Fracture | Uneven |
| Hardness | 5.5 |
| Refractive Index | 1.500 - 1.670 |
| Specific Gravity | 2.50 - 3.00 |
| Lustre | Resinous to vitreous |
Malachite
| Varieties | Banded light and dark green |
| Chemical Composition | Cu2(CO3)(OH)2 |
| Crystal System | Monoclinic |
| Habit | Botryoidal, stalactitic, globular |
| Cleavage | Distinct |
| Fracture | Conchoidal, splintery |
| Hardness | 3.5-4 |
| Optic Nature | Biaxial Negative |
| Refactive Index | 1.655 - 1.909 |
| Birefringence | 0.254 |
| Dispersion | Weak |
| Specific Gravity | 3.60 - 4.05 |
| Lustre | Dull, silky, vitreous |
| Transparency | Translucent to opaque |
| Pleochroism | None |
Nephrite Jade
| Varieties | Green to black |
| Chemical Composition | Complex Ca Mg/Fe (calcium magnesium/iron) silicate |
| Crystal System | Monoclinic |
| Habit | Polycrystalline |
| Fracture | Splintery |
| Hardness | 6.5 |
| Refractive Index | +/- 1.62 |
| Specific Gravity | 2.90 - 3.20 |
| Lustre | Greasy to vitreous |
Opal
| Varieties | Precious opal (white opal, black opal, boulder opal, jelly opal, crystal opal) all with play of colour. |
| Fire opal (yellow to orange brown) no play of colour | |
| Chemical Composition | SiO2+H2O |
| Crystal System | Amorphous |
| Hardness | 5 - 6.5 |
| Refractive Index | 1.45 (+.020;-0.080) |
| Specific Gravity | 2.15 (+0.07;-0.90) |
| Lustre | Vitreous |
| Phenomenon | Play of Color |
Peridot
| Varieties | Yellow-green, olive-green, brownish-green |
| Chemical Composition | (Mg,Fe)2SiO4 |
| Crystal System | Orthorhombic |
| Habit | Prismatic |
| Cleavage | Poor |
| Fracture | Conchoidal |
| Hardness | 6.5 |
| Optic Nature | Biaxial Positive |
| Refractive Index | 1.65 - 1.69 |
| Birefringence | 0.036 |
| Dispersion | Medium, 0.020 |
| Specific Gravity | 3.34 |
| Lustre | Vitreous |
| Pleochroism | Weak |
Pyralspite
| Composition | Refractive Index | Specific Gravity | Hardness | Dispersion | Colour | |
| Pyrope | Mg3AI2(SiO4)3 | 1.73 to 1.76 | 3.65 to 3.84 | 7.5 | 0.022 | Transparent red, purple red. Allochromatic (Cr, Fe) |
| Almandine | Fe3AI2(SiO4)3 | 1.76 to 1.81 | 4.09 to 4.31 | 7.0 to 8.0 | 0.027 | Transparent brown-red to purple red. Idiochromatic (Fe) |
| Spessarite | Mn3Al2(SiO4)3 | 1.80 to 1.82 | 4.18 | 6.5 to 7.5 | 0.027 | Transparent orange, red-orange. Idiochromatic (Mn) |
Quartz (Crystalline)
| Varieties | Amethyst (purple) |
| Ametrine (half purple half yellow) | |
| Citrine (yellow, golden-yellow) | |
| Prasiolite (green) | |
| Rock crystal (colourless) | |
| Rose quartz (pink) | |
| Smokey quartz (smokey brown, grey, black) | |
| Chemical Composition | SiO2 Silicon dioxide |
| Crystal System | Trigonal |
| Habit | Prismatic |
| Cleavage | Poor |
| Fracture | Conchoidal |
| Hardness | 7 |
| Optic Nature | Uniaxial Positive |
| Refractive Index | 1.544 - 1.553 |
| Birefringence | 0.009 |
| Dispersion | 0.013 |
| Specific Gravity | 2.65 |
| Lustre | Vitreous |
| Pleochroism | None |
Spinel
| Varieties | Colourless, green, blue, red, black |
| Chemical Composition | Mg(Al2O4) Magnesium aluminum oxide |
| Crystal System | Cubic |
| Habit | Octahedral, contact twins |
| Cleavage | Imperfect |
| Fracture | Conchoidal, uneven |
| Hardness | 8 |
| Optic Nature | Isotropic |
| Refractive Index | 1.712 - 1.736 |
| Birefringence | None |
| Dispersion | 0.026 |
| Specific Gravity | 3.58 - 3.61 |
| Lustre | Vitreous |
| Pleochroism | None |
Spodumene
| Varieties | Hiddenite (yellow to green) |
| Kunzite (pink to violet) | |
| Chemical Composition | LiA(SiO3)2 |
| Crystal System | Monoclinic |
| Habit | Prismatic, tabular |
| Cleavage | Perfect, prismatic |
| Fracture | Uneven |
| Hardness | 7 |
| Optic Nature | Biaxial Positive |
| Refractive Index | 1.66 - 1.68 |
| Birefringence | 0.015 |
| Dispersion | Low, 0.017 |
| Specific Gravity | 3.18 |
| Lustre | Vitreous |
| Pleochroism | Strong |
Topaz
| Varieties | Colourless, yellow, green, blue, red, pink, orange, brown |
| Chemical Composition | Al2(F,OH)2SiO4 |
| Crystal System | Orthorhombic |
| Habit | Prismatic with pyramid/domed terminations |
| Cleavage | Perfect, basal plane |
| Fracture | Sub-conchoidal to uneven |
| Hardness | 8 |
| Optic Nature | Biaxial Positive |
| Refractive Index | 1.606 - 1.644 |
| Birefringence | 0.008 - 0.010 |
| Dispersion | Low, 0.014 |
| Specific Gravity | 3.49 - 3.57 |
| Lustre | Vitreous |
| Pleochroism | Distinct to strong (depending on body color) |
Tourmaline
| Varieties | All colours, bi-colour, tri-colour |
| Chemical Composition | Complex borosilicate |
| Crystal System | Trigonal |
| Habit | Trigonal prisms with convex faces |
| Fracture | Conchoidal |
| Hardness | 7.5 |
| Optic Nature | Uniaxial Negative |
| Refractive Index | 1.62 - 1.64 |
| Birefringence | 0.014 - 0.021 (up to 0.039) |
| Dispersion | Low, 0.018 |
| Specific Gravity | 3.06 (3.01-3.11) |
| Lustre | Vitreous |
| Pleochroism | Weak to Strong |
Turquoise
| Chemical Composition | CuAl6(PO4)4(OH)8.5H2O |
| Crystal System | Triclinic |
| Habit | Botryoidal, massive, microcrystalline to granular |
| Fracture | Conchoidal |
| Hardness | 5.0 - 6.0 |
| Refractive Index | 1.610 - 1.650 |
| Specific Gravity | 2.30-2.90 |
| Lustre | Waxy |
