Difference between revisions of "Gemstone"
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[[File:Diamondcutkes.jpg|thumb|Gemstone facet cuts]] | [[File:Diamondcutkes.jpg|thumb|Gemstone facet cuts]] | ||
− | + | Properties of Common Gemstones | |
+ | {| class="wikitable" | ||
+ | |- | ||
+ | ! colspan="2" | Mineral | ||
+ | ! colspan="2" | Gem | ||
+ | ! colspan="2" | Color | ||
+ | ! colspan="2" | Mohs hardness | ||
+ | ! colspan="2" | Specific gravity | ||
+ | ! colspan="2" | Refractive index | ||
+ | ! colspan="2" | Crystal system | ||
+ | ! colspan="2" | Other | ||
+ | ! colspan="2" | Fluorescence | ||
+ | ! colspan="2" | Dispersion | ||
+ | ! colspan="2" | Inclusions | ||
+ | |- | ||
+ | | rowspan="5" colspan="2" | beryl | ||
+ | | colspan="2" | aquamarine | ||
+ | | colspan="2" | sky blue | ||
+ | | rowspan="5" colspan="2" | 7.5-8.0 | ||
+ | | rowspan="3" colspan="2" | 2.68-2.71 | ||
+ | | rowspan="3" colspan="2" | epsilon = 1.570-1.580<br /> omega = 1.574-1.586 | ||
+ | | rowspan="5" colspan="2" | hexagonal crystal system; conchoidal fracture | ||
+ | | rowspan="5" colspan="2" | transparent; weakly pleochroic | ||
+ | | rowspan="5" colspan="2" | none to weak; synthetic stones may appear opaque and dull red in longwave UV | ||
+ | | rowspan="5" colspan="2" | <br /> <br /> <br /> <br /> | ||
+ | | rowspan="5" colspan="2" | Aquamarines are often flawless; Other contain many inclusions such as mica, pyrite and calcite | ||
+ | |- | ||
+ | | colspan="2" | goshenite | ||
+ | | colspan="2" | colorless | ||
+ | |- | ||
+ | | colspan="2" | heliodor | ||
+ | | colspan="2" | yellow | ||
+ | |- | ||
+ | | colspan="2" | emerald | ||
+ | | colspan="2" | green | ||
+ | | colspan="2" | 2.68-2.78 | ||
+ | | colspan="2" | epsilon = 1.571-1.581<br /> omega = 1.577-1.588 | ||
+ | |- | ||
+ | | colspan="2" | morganite | ||
+ | | colspan="2" | pink | ||
+ | | colspan="2" | 2.66-2.83 | ||
+ | | colspan="2" | epsilon = 1.580-1.590<br /> omega = 1.589-1.601 | ||
+ | |- | ||
+ | | colspan="2" | chrysoberyl | ||
+ | | colspan="2" | alexandrite | ||
+ | | colspan="2" | green in daylight, red in incandescent light | ||
+ | | colspan="2" | 8.5 | ||
+ | | colspan="2" | 3.5-3.8 | ||
+ | | colspan="2" | alpha = 1.745<br /> beta = 1.748<br /> gamma = 1.754 | ||
+ | | colspan="2" | orthorhombic, flattened crystals, often twinned | ||
+ | | colspan="2" | transparent; chrysoberyl cat's-eye is<br /> chatoyant | ||
+ | | colspan="2" | strongly pleochroic | ||
+ | | colspan="2" | d = 0.015 | ||
+ | | colspan="2" | | ||
+ | |- | ||
+ | | colspan="2" | cristobalite | ||
+ | | colspan="2" | opal | ||
+ | | colspan="2" | milky white to colorless;; variable pale shades | ||
+ | | colspan="2" | 5.5-6.5 | ||
+ | | colspan="2" | 1.98-2.25 | ||
+ | | colspan="2" | 1.435-1.455 | ||
+ | | colspan="2" | tetragonal submicrocrystalline aggregates; irregular concretions; glass-<br /> like fracture | ||
+ | | colspan="2" | opaque; contains some water causing the physical properties to<br /> vary | ||
+ | | colspan="2" | may fluoresce white or pale green; may phosphoresce | ||
+ | | colspan="2" | | ||
+ | | colspan="2" | possible | ||
+ | |- | ||
+ | | rowspan="3" colspan="2" | corundum | ||
+ | | colspan="2" | sapphire | ||
+ | | colspan="2" | blue | ||
+ | | rowspan="3" colspan="2" | 9.0 | ||
+ | | rowspan="3" colspan="2" | 4.0 | ||
+ | | rowspan="3" colspan="2" | epsilon = 1.757-1.768<br /> omega = 1.765-1.776 | ||
+ | | rowspan="3" colspan="2" | hexagonal; conchoidal fracture | ||
+ | | rowspan="3" colspan="2" | transparent; marked dichroism | ||
+ | | rowspan="3" colspan="2" | orange to red; heat treated stones may fluoresce green | ||
+ | | rowspan="3" colspan="2" | d = 0.018 | ||
+ | | rowspan="3" colspan="2" | many including minerals (rutile), fluids, angular<br /> banding | ||
+ | |- | ||
+ | | colspan="2" | ruby | ||
+ | | colspan="2" | red | ||
+ | |- | ||
+ | | colspan="2" | padmaradschah | ||
+ | | colspan="2" | orange | ||
+ | |- | ||
+ | | colspan="2" | diamond | ||
+ | | colspan="2" | diamond | ||
+ | | colspan="2" | variable (colorless, yellow, blue) | ||
+ | | colspan="2" | 10.0 | ||
+ | | colspan="2" | 3.52 | ||
+ | | colspan="2" | 2.4175 | ||
+ | | colspan="2" | isometric flattened octahedrons; dodecahedrons | ||
+ | | colspan="2" | transparent; perfect cleavage in four directions | ||
+ | | colspan="2" | may fluoresce pale colors in longwave UV; may<br /> phosphoresce | ||
+ | | colspan="2" | d = 0.044 | ||
+ | | colspan="2" | trigonal on surface; numerous inclusions | ||
+ | |- | ||
+ | | rowspan="3" colspan="2" | potash feldspar | ||
+ | | colspan="2" | orthoclase | ||
+ | | colspan="2" | pale yellow to flesh red | ||
+ | | rowspan="3" colspan="2" | 6.0-6.5 | ||
+ | | rowspan="3" colspan="2" | 2.6 | ||
+ | | rowspan="3" colspan="2" | alpha = 1.518<br /> beta = 1.522<br /> gamma = 1.522 | ||
+ | | colspan="2" | monoclinic crystals | ||
+ | | colspan="2" | two perfect cleavages at right angles | ||
+ | | colspan="2" | | ||
+ | | colspan="2" | | ||
+ | | colspan="2" | | ||
+ | |- | ||
+ | | colspan="2" | moonstone | ||
+ | | colspan="2" | colorless, white to yellowish | ||
+ | | colspan="2" | nodules or masses | ||
+ | | colspan="2" | blue opalecsence | ||
+ | | colspan="2" | | ||
+ | | colspan="2" | | ||
+ | | colspan="2" | | ||
+ | |- | ||
+ | | colspan="2" | amazonite | ||
+ | | colspan="2" | yellow green to blue green | ||
+ | | colspan="2" | triclinic, large crystals | ||
+ | | colspan="2" | variety of microcline | ||
+ | | colspan="2" | | ||
+ | | colspan="2" | | ||
+ | | colspan="2" | | ||
+ | |- | ||
+ | | rowspan="2" colspan="2" | plagioclase feldspar | ||
+ | | colspan="2" | sunstone (aventurine) | ||
+ | | colspan="2" | colorless to pale pink | ||
+ | | rowspan="2" colspan="2" | 6.0-6.5 | ||
+ | | rowspan="2" colspan="2" | 2.6-2.7 | ||
+ | | rowspan="2" colspan="2" | alpha = 1.527-1.577<br /> beta=1.531-1.585<br /> gamma = 1.538-1.590 | ||
+ | | rowspan="2" colspan="2" | triclinic prismatic crystals; two perfect cleavages at right angles | ||
+ | | rowspan="2" colspan="2" | transparent to opaque; iridescent; | ||
+ | | colspan="2" | | ||
+ | | colspan="2" | | ||
+ | | colspan="2" | inclusions give spangled appearance | ||
+ | |- | ||
+ | | colspan="2" | labradorite | ||
+ | | colspan="2" | grayish shades | ||
+ | | colspan="2" | | ||
+ | | colspan="2" | | ||
+ | | colspan="2" | | ||
+ | |- | ||
+ | | colspan="2" | fluorite | ||
+ | | colspan="2" | fluorite | ||
+ | | colspan="2" | lavender to green | ||
+ | | colspan="2" | | ||
+ | | colspan="2" | | ||
+ | | colspan="2" | 1.434 | ||
+ | | colspan="2" | conchoidal fracture | ||
+ | | colspan="2" | transparent | ||
+ | | colspan="2" | strong | ||
+ | | colspan="2" | | ||
+ | | colspan="2" | color zoning | ||
+ | |- | ||
+ | | rowspan="5" colspan="2" | garnet | ||
+ | | colspan="2" | almandine (carbuncle) | ||
+ | | colspan="2" | deep red with a trace of purple | ||
+ | | colspan="2" | 7.0-7.5 | ||
+ | | colspan="2" | 4.3 | ||
+ | | colspan="2" | 1.79-1.83 | ||
+ | | rowspan="5" colspan="2" | isometric euhedral crystals, with dodecahedrons and trapezodrons most common; conchoidal fracture | ||
+ | | rowspan="5" colspan="2" | light colored varieties are transparent; no birefringence, no pleochroism | ||
+ | | colspan="2" | none | ||
+ | | colspan="2" | d = 0.024 | ||
+ | | rowspan="5" colspan="2" | needles; single and multiphase prisms | ||
+ | |- | ||
+ | | colspan="2" | andradite (Uralian emerald) | ||
+ | | colspan="2" | deep emerald-green | ||
+ | | colspan="2" | 6.5-7.0 | ||
+ | | colspan="2" | 3.9 | ||
+ | | colspan="2" | 1.887 | ||
+ | | colspan="2" | none | ||
+ | | colspan="2" | d = 0.057 | ||
+ | |- | ||
+ | | colspan="2" | grossularite (hessonite) | ||
+ | | colspan="2" | yellow-brown to orange, red, or green | ||
+ | | colspan="2" | 7.0-7.5 | ||
+ | | colspan="2" | 3.6 | ||
+ | | colspan="2" | 1.734-1.740 | ||
+ | | colspan="2" | pale orange in long UV; yellow in short UV | ||
+ | | colspan="2" | d = 0.028 | ||
+ | |- | ||
+ | | colspan="2" | pyrope | ||
+ | | colspan="2" | dark blood red | ||
+ | | colspan="2" | 7.0-7.5 | ||
+ | | colspan="2" | 3.78 | ||
+ | | colspan="2" | 1.714-1.742 | ||
+ | | colspan="2" | none | ||
+ | | colspan="2" | d = 0.027 | ||
+ | |- | ||
+ | | colspan="2" | spessartine | ||
+ | | colspan="2" | yellow-orange to brown- red | ||
+ | | colspan="2" | 7.0-7.5 | ||
+ | | colspan="2" | 4.15 | ||
+ | | colspan="2" | 1.800-1.810 | ||
+ | | colspan="2" | none | ||
+ | | colspan="2" | d = 0.027 | ||
+ | |- | ||
+ | | rowspan="2" colspan="2" | jade | ||
+ | | colspan="2" | jadeite (Imperial jade) | ||
+ | | colspan="2" | green but may be white, black, red, brown, yellow, blue or mauve | ||
+ | | colspan="2" | 6.0 | ||
+ | | colspan="2" | 3.33-3.34 | ||
+ | | colspan="2" | alpha = 1.640-1.658<br /> beta=1.645-1.663<br /> gamma = 1.652-1.673 | ||
+ | | colspan="2" | monoclinic compact or fibrous masses; granular to splintery fracture | ||
+ | | colspan="2" | translucent to opaque; greasy luster | ||
+ | | colspan="2" | may have pale white color in long UV light | ||
+ | | colspan="2" | | ||
+ | | colspan="2" | | ||
+ | |- | ||
+ | | colspan="2" | nephrite | ||
+ | | colspan="2" | deep spinach green to near-white | ||
+ | | colspan="2" | 6.0-6.5 | ||
+ | | colspan="2" | 2.96-3.02 | ||
+ | | colspan="2" | alpha = 1.600-1.672<br /> beta=1.614-1.686<br /> gamma = 1.627-1.693 | ||
+ | | colspan="2" | monoclinic compact masses; conchoidal to granular fracture | ||
+ | | colspan="2" | translucent to opaque; greasy or waxy appearance | ||
+ | | colspan="2" | none | ||
+ | | colspan="2" | | ||
+ | | colspan="2" | some dark inclusions | ||
+ | |- | ||
+ | | colspan="2" | lazurite | ||
+ | | colspan="2" | lapis lazuli | ||
+ | | colspan="2" | azure blue with flecks of white and gold | ||
+ | | colspan="2" | 5.0-5.5 | ||
+ | | colspan="2" | 2.7-2.9 | ||
+ | | colspan="2" | 1.50-1.67 | ||
+ | | colspan="2" | isometric with compact masses; opaque | ||
+ | | colspan="2" | decomposed by hydrochloric acid | ||
+ | | colspan="2" | | ||
+ | | colspan="2" | | ||
+ | | colspan="2" | | ||
+ | |- | ||
+ | | colspan="2" | olivine | ||
+ | | colspan="2" | peridot; chrysolite | ||
+ | | colspan="2" | yellow green; dark bottle green; olive green | ||
+ | | colspan="2" | 6.5-7.0 | ||
+ | | colspan="2" | 3.3-3.4 | ||
+ | | colspan="2" | alpha = 1.635-1.671<br /> beta = 1.652-1.698<br /> gamma = 1.671-1.707 | ||
+ | | colspan="2" | orthorhombic system with massive or granular forms; fracture=uneven to conchoidal | ||
+ | | colspan="2" | transparent | ||
+ | | colspan="2" | | ||
+ | | colspan="2" | d = 0.020 | ||
+ | | colspan="2" | | ||
+ | |- | ||
+ | | rowspan="8" colspan="2" | quartz | ||
+ | | colspan="2" | amethyst | ||
+ | | colspan="2" | purple | ||
+ | | rowspan="8" colspan="2" | 7.0 | ||
+ | | rowspan="8" colspan="2" | 2.65 | ||
+ | | rowspan="8" colspan="2" | epsilon = 1.553<br /> omega = 1.544 | ||
+ | | rowspan="5" colspan="2" | conchoidal fracture | ||
+ | | rowspan="5" colspan="2" | transparent; heat treatment may bleach stones | ||
+ | | colspan="2" | | ||
+ | | colspan="2" | d = 0.013 | ||
+ | | colspan="2" | | ||
+ | |- | ||
+ | | colspan="2" | cairngorm (smoky quartz) | ||
+ | | colspan="2" | smoky brown | ||
+ | | colspan="2" | | ||
+ | | colspan="2" | | ||
+ | | colspan="2" | | ||
+ | |- | ||
+ | | colspan="2" | citrine | ||
+ | | colspan="2" | yellow | ||
+ | | colspan="2" | | ||
+ | | colspan="2" | | ||
+ | | colspan="2" | | ||
+ | |- | ||
+ | | colspan="2" | rock crystal | ||
+ | | colspan="2" | colorless | ||
+ | | colspan="2" | | ||
+ | | colspan="2" | | ||
+ | | colspan="2" | | ||
+ | |- | ||
+ | | colspan="2" | rose quartz | ||
+ | | colspan="2" | pink | ||
+ | | colspan="2" | | ||
+ | | colspan="2" | | ||
+ | | colspan="2" | | ||
+ | |- | ||
+ | | colspan="2" | agate (moss agate, mocha stone) | ||
+ | | colspan="2" | variable | ||
+ | | rowspan="3" colspan="2" | compact masses; nodules | ||
+ | | rowspan="3" colspan="2" | translucent to opaque | ||
+ | | colspan="2" | | ||
+ | | colspan="2" | | ||
+ | | colspan="2" | | ||
+ | |- | ||
+ | | colspan="2" | chalcedony (onyx, carnelian, sardonyx, chrysoprase, bloodstone,<br /> heliotrope) | ||
+ | | colspan="2" | variable | ||
+ | | colspan="2" | | ||
+ | | colspan="2" | | ||
+ | | colspan="2" | | ||
+ | |- | ||
+ | | colspan="2" | jasper | ||
+ | | colspan="2" | variable | ||
+ | | colspan="2" | | ||
+ | | colspan="2" | | ||
+ | | colspan="2" | | ||
+ | |- | ||
+ | | colspan="2" | spinel | ||
+ | | colspan="2" | Balas ruby; | ||
+ | | colspan="2" | typically red; also variable: yellow (rubicelle), violet (almandine), pleonast (blue, black), gahnite (blue-green) | ||
+ | | colspan="2" | 8 | ||
+ | | colspan="2" | 3.6 | ||
+ | | colspan="2" | 1.715-1.725 | ||
+ | | colspan="2" | isometric octahedral crystals; rounded grains; conchoidal fracture | ||
+ | | colspan="2" | transparent | ||
+ | | colspan="2" | natural fluoresces red in longwave UV; synthetic may show colors in<br /> shortwave UV | ||
+ | | colspan="2" | d = 0.020 | ||
+ | | colspan="2" | fingerprint pattern inclusions | ||
+ | |- | ||
+ | | colspan="2" | topaz | ||
+ | | colspan="2" | topaz, hyacinth | ||
+ | | colspan="2" | yellow, green, blue, violet or red | ||
+ | | colspan="2" | 8 | ||
+ | | colspan="2" | 3.4-3.6 | ||
+ | | colspan="2" | alpha = 1.606-1.629<br /> beta = .609-1.631<br /> gamma = 1.616-1.638 | ||
+ | | colspan="2" | orthorhombic prismatic crystals; perfect cleavage in one direction | ||
+ | | colspan="2" | transparent; highly pleochroic; turns soft red when heated | ||
+ | | colspan="2" | may fluoresce yellow in longwave UV | ||
+ | | colspan="2" | d = 0.014 | ||
+ | | colspan="2" | single and multiphase | ||
+ | |- | ||
+ | | rowspan="6" colspan="2" | tourmaline | ||
+ | | colspan="2" | achroite | ||
+ | | colspan="2" | colorless or green | ||
+ | | rowspan="6" colspan="2" | 7-7.5 | ||
+ | | rowspan="6" colspan="2" | 2.9-3.2 | ||
+ | | rowspan="6" colspan="2" | epsilon = 1.610-1.650<br /> omega = 1.635-1.675 | ||
+ | | rowspan="6" colspan="2" | hexagonal prismatic crystals, often rounded or oval; conchoidal fracture | ||
+ | | rowspan="6" colspan="2" | transparent; pleochroic | ||
+ | | rowspan="6" colspan="2" | none to weak | ||
+ | | rowspan="6" colspan="2" | d = 0.016 | ||
+ | | rowspan="6" colspan="2" | gas and liquid pockets with color zoning | ||
+ | |- | ||
+ | | colspan="2" | dravite | ||
+ | | colspan="2" | brown | ||
+ | |- | ||
+ | | colspan="2" | indicolite | ||
+ | | colspan="2" | blue | ||
+ | |- | ||
+ | | colspan="2" | rubellite | ||
+ | | colspan="2" | pink | ||
+ | |- | ||
+ | | colspan="2" | schorl | ||
+ | | colspan="2" | black | ||
+ | |- | ||
+ | | colspan="2" | siberite | ||
+ | | colspan="2" | violet | ||
+ | |- | ||
+ | | colspan="2" | turquoise | ||
+ | | colspan="2" | turquoise | ||
+ | | colspan="2" | blue to greenish-blue | ||
+ | | colspan="2" | 5.0-6.0 | ||
+ | | colspan="2" | 2.6-2.9 | ||
+ | | colspan="2" | alpha = 1.61<br /> beta = 1.62<br /> gamma = 1.65 | ||
+ | | colspan="2" | cryptocrystalline to fine granular; fracture=conchoidal | ||
+ | | colspan="2" | opaque; color fades in sunlight | ||
+ | | colspan="2" | | ||
+ | | colspan="2" | | ||
+ | | colspan="2" | | ||
+ | |- | ||
+ | | rowspan="4" colspan="2" | zircon | ||
+ | | colspan="2" | jargon | ||
+ | | colspan="2" | variable | ||
+ | | rowspan="4" colspan="2" | 6.0-7.5 | ||
+ | | rowspan="4" colspan="2" | 4.6-4.7 | ||
+ | | rowspan="4" colspan="2" | epsilon = 1.968-2.015<br /> omega<br /> = 1.923-1.960 | ||
+ | | rowspan="4" colspan="2" | tetragonal system with square prismatic crystals; fracture=uneven | ||
+ | | rowspan="4" colspan="2" | transparent; pleochroic | ||
+ | | rowspan="4" colspan="2" | some show dull yellow color; some may phosphoresce | ||
+ | | rowspan="4" colspan="2" | d = 0.048 | ||
+ | | rowspan="4" colspan="2" | rutile crystals; single and multiphase | ||
+ | |- | ||
+ | | colspan="2" | Matura diamond | ||
+ | | colspan="2" | colorless | ||
+ | |- | ||
+ | | colspan="2" | hyacinth | ||
+ | | colspan="2" | yellow orange | ||
+ | |- | ||
+ | | colspan="2" | jacinth | ||
+ | | colspan="2" | red brown | ||
+ | |} | ||
== Synonyms and Related Terms == | == Synonyms and Related Terms == | ||
gemstones; gem; gem; ædelsten (Dan.); Schmucksteine (Deut.); gema (Esp.); gemme (Fr.); edelsteen (Ned.); gema (Port.); Ädelsten (Sven.) | gemstones; gem; gem; ædelsten (Dan.); Schmucksteine (Deut.); gema (Esp.); gemme (Fr.); edelsteen (Ned.); gema (Port.); Ädelsten (Sven.) | ||
− | == | + | == For easy print or to download == |
[[media:download_file_414.pdf|Properties of Common Gemstones]] | [[media:download_file_414.pdf|Properties of Common Gemstones]] | ||
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* ''Encyclopedia Britannica'', http://www.britannica.com Comment: "gemstone." Accessed 10 Nov. 2004 . | * ''Encyclopedia Britannica'', http://www.britannica.com Comment: "gemstone." Accessed 10 Nov. 2004 . | ||
− | |||
* C.W.Chesterman, K.E.Lowe, ''Audubon Society Field Guide to North American Rocks and Minerals'', Alfred A. Knopf, New York, 1979 | * C.W.Chesterman, K.E.Lowe, ''Audubon Society Field Guide to North American Rocks and Minerals'', Alfred A. Knopf, New York, 1979 | ||
− | |||
* ''The Dictionary of Art'', Grove's Dictionaries Inc., New York, 1996 Comment: Gems: cutting. by Ken Scaratt | * ''The Dictionary of Art'', Grove's Dictionaries Inc., New York, 1996 Comment: Gems: cutting. by Ken Scaratt | ||
− | |||
* Wikipedia: http://en.wikipedia.org/wiki/Gemstone (Accessed Nov. 2, 2005) | * Wikipedia: http://en.wikipedia.org/wiki/Gemstone (Accessed Nov. 2, 2005) | ||
Latest revision as of 13:40, 13 October 2024
Description
An ornamental, often valuable, mineral used for decoration in jewelry, small objects and clothing. Gems are found in alluvial deposits and dug from veins. Major mining locations include Sri Lanka, southeast Asia, South Africa, Australia, Russia, Brazil and Colombia. Gemstones are characterized based on their color, clarity, cut and weight. Stones of exceptional size, beauty or rarity are highly valued. Techniques for cutting and polishing gemstones were developed in India in the 14th century. Gemstones can usually be classified into three types:
- Transparent crystalline stones; usually cut: Amethyst, Aquamarine, Citrine, Emerald, Diamonds, Garnets, Peridot, Quartz, Rubies, Sapphires, Spinel, Tanzanite, Topaz, Tourmaline, and Zircon.
- Non-transparent minerals, usually polished: Agate, Carnelian, Cat's eye, Chrysoberyl, Chrysocolla, Jasper, Lapis lazuli, and Turquoise
- Non-stone materials: Ivory, Amber, Jet, and Coral
Properties of Common Gemstones
Mineral | Gem | Color | Mohs hardness | Specific gravity | Refractive index | Crystal system | Other | Fluorescence | Dispersion | Inclusions | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
beryl | aquamarine | sky blue | 7.5-8.0 | 2.68-2.71 | epsilon = 1.570-1.580 omega = 1.574-1.586 |
hexagonal crystal system; conchoidal fracture | transparent; weakly pleochroic | none to weak; synthetic stones may appear opaque and dull red in longwave UV | Aquamarines are often flawless; Other contain many inclusions such as mica, pyrite and calcite | ||||||||||||
goshenite | colorless | ||||||||||||||||||||
heliodor | yellow | ||||||||||||||||||||
emerald | green | 2.68-2.78 | epsilon = 1.571-1.581 omega = 1.577-1.588 | ||||||||||||||||||
morganite | pink | 2.66-2.83 | epsilon = 1.580-1.590 omega = 1.589-1.601 | ||||||||||||||||||
chrysoberyl | alexandrite | green in daylight, red in incandescent light | 8.5 | 3.5-3.8 | alpha = 1.745 beta = 1.748 gamma = 1.754 |
orthorhombic, flattened crystals, often twinned | transparent; chrysoberyl cat's-eye is chatoyant |
strongly pleochroic | d = 0.015 | ||||||||||||
cristobalite | opal | milky white to colorless;; variable pale shades | 5.5-6.5 | 1.98-2.25 | 1.435-1.455 | tetragonal submicrocrystalline aggregates; irregular concretions; glass- like fracture |
opaque; contains some water causing the physical properties to vary |
may fluoresce white or pale green; may phosphoresce | possible | ||||||||||||
corundum | sapphire | blue | 9.0 | 4.0 | epsilon = 1.757-1.768 omega = 1.765-1.776 |
hexagonal; conchoidal fracture | transparent; marked dichroism | orange to red; heat treated stones may fluoresce green | d = 0.018 | many including minerals (rutile), fluids, angular banding | |||||||||||
ruby | red | ||||||||||||||||||||
padmaradschah | orange | ||||||||||||||||||||
diamond | diamond | variable (colorless, yellow, blue) | 10.0 | 3.52 | 2.4175 | isometric flattened octahedrons; dodecahedrons | transparent; perfect cleavage in four directions | may fluoresce pale colors in longwave UV; may phosphoresce |
d = 0.044 | trigonal on surface; numerous inclusions | |||||||||||
potash feldspar | orthoclase | pale yellow to flesh red | 6.0-6.5 | 2.6 | alpha = 1.518 beta = 1.522 gamma = 1.522 |
monoclinic crystals | two perfect cleavages at right angles | ||||||||||||||
moonstone | colorless, white to yellowish | nodules or masses | blue opalecsence | ||||||||||||||||||
amazonite | yellow green to blue green | triclinic, large crystals | variety of microcline | ||||||||||||||||||
plagioclase feldspar | sunstone (aventurine) | colorless to pale pink | 6.0-6.5 | 2.6-2.7 | alpha = 1.527-1.577 beta=1.531-1.585 gamma = 1.538-1.590 |
triclinic prismatic crystals; two perfect cleavages at right angles | transparent to opaque; iridescent; | inclusions give spangled appearance | |||||||||||||
labradorite | grayish shades | ||||||||||||||||||||
fluorite | fluorite | lavender to green | 1.434 | conchoidal fracture | transparent | strong | color zoning | ||||||||||||||
garnet | almandine (carbuncle) | deep red with a trace of purple | 7.0-7.5 | 4.3 | 1.79-1.83 | isometric euhedral crystals, with dodecahedrons and trapezodrons most common; conchoidal fracture | light colored varieties are transparent; no birefringence, no pleochroism | none | d = 0.024 | needles; single and multiphase prisms | |||||||||||
andradite (Uralian emerald) | deep emerald-green | 6.5-7.0 | 3.9 | 1.887 | none | d = 0.057 | |||||||||||||||
grossularite (hessonite) | yellow-brown to orange, red, or green | 7.0-7.5 | 3.6 | 1.734-1.740 | pale orange in long UV; yellow in short UV | d = 0.028 | |||||||||||||||
pyrope | dark blood red | 7.0-7.5 | 3.78 | 1.714-1.742 | none | d = 0.027 | |||||||||||||||
spessartine | yellow-orange to brown- red | 7.0-7.5 | 4.15 | 1.800-1.810 | none | d = 0.027 | |||||||||||||||
jade | jadeite (Imperial jade) | green but may be white, black, red, brown, yellow, blue or mauve | 6.0 | 3.33-3.34 | alpha = 1.640-1.658 beta=1.645-1.663 gamma = 1.652-1.673 |
monoclinic compact or fibrous masses; granular to splintery fracture | translucent to opaque; greasy luster | may have pale white color in long UV light | |||||||||||||
nephrite | deep spinach green to near-white | 6.0-6.5 | 2.96-3.02 | alpha = 1.600-1.672 beta=1.614-1.686 gamma = 1.627-1.693 |
monoclinic compact masses; conchoidal to granular fracture | translucent to opaque; greasy or waxy appearance | none | some dark inclusions | |||||||||||||
lazurite | lapis lazuli | azure blue with flecks of white and gold | 5.0-5.5 | 2.7-2.9 | 1.50-1.67 | isometric with compact masses; opaque | decomposed by hydrochloric acid | ||||||||||||||
olivine | peridot; chrysolite | yellow green; dark bottle green; olive green | 6.5-7.0 | 3.3-3.4 | alpha = 1.635-1.671 beta = 1.652-1.698 gamma = 1.671-1.707 |
orthorhombic system with massive or granular forms; fracture=uneven to conchoidal | transparent | d = 0.020 | |||||||||||||
quartz | amethyst | purple | 7.0 | 2.65 | epsilon = 1.553 omega = 1.544 |
conchoidal fracture | transparent; heat treatment may bleach stones | d = 0.013 | |||||||||||||
cairngorm (smoky quartz) | smoky brown | ||||||||||||||||||||
citrine | yellow | ||||||||||||||||||||
rock crystal | colorless | ||||||||||||||||||||
rose quartz | pink | ||||||||||||||||||||
agate (moss agate, mocha stone) | variable | compact masses; nodules | translucent to opaque | ||||||||||||||||||
chalcedony (onyx, carnelian, sardonyx, chrysoprase, bloodstone, heliotrope) |
variable | ||||||||||||||||||||
jasper | variable | ||||||||||||||||||||
spinel | Balas ruby; | typically red; also variable: yellow (rubicelle), violet (almandine), pleonast (blue, black), gahnite (blue-green) | 8 | 3.6 | 1.715-1.725 | isometric octahedral crystals; rounded grains; conchoidal fracture | transparent | natural fluoresces red in longwave UV; synthetic may show colors in shortwave UV |
d = 0.020 | fingerprint pattern inclusions | |||||||||||
topaz | topaz, hyacinth | yellow, green, blue, violet or red | 8 | 3.4-3.6 | alpha = 1.606-1.629 beta = .609-1.631 gamma = 1.616-1.638 |
orthorhombic prismatic crystals; perfect cleavage in one direction | transparent; highly pleochroic; turns soft red when heated | may fluoresce yellow in longwave UV | d = 0.014 | single and multiphase | |||||||||||
tourmaline | achroite | colorless or green | 7-7.5 | 2.9-3.2 | epsilon = 1.610-1.650 omega = 1.635-1.675 |
hexagonal prismatic crystals, often rounded or oval; conchoidal fracture | transparent; pleochroic | none to weak | d = 0.016 | gas and liquid pockets with color zoning | |||||||||||
dravite | brown | ||||||||||||||||||||
indicolite | blue | ||||||||||||||||||||
rubellite | pink | ||||||||||||||||||||
schorl | black | ||||||||||||||||||||
siberite | violet | ||||||||||||||||||||
turquoise | turquoise | blue to greenish-blue | 5.0-6.0 | 2.6-2.9 | alpha = 1.61 beta = 1.62 gamma = 1.65 |
cryptocrystalline to fine granular; fracture=conchoidal | opaque; color fades in sunlight | ||||||||||||||
zircon | jargon | variable | 6.0-7.5 | 4.6-4.7 | epsilon = 1.968-2.015 omega = 1.923-1.960 |
tetragonal system with square prismatic crystals; fracture=uneven | transparent; pleochroic | some show dull yellow color; some may phosphoresce | d = 0.048 | rutile crystals; single and multiphase | |||||||||||
Matura diamond | colorless | ||||||||||||||||||||
hyacinth | yellow orange | ||||||||||||||||||||
jacinth | red brown |
Synonyms and Related Terms
gemstones; gem; gem; ædelsten (Dan.); Schmucksteine (Deut.); gema (Esp.); gemme (Fr.); edelsteen (Ned.); gema (Port.); Ädelsten (Sven.)
For easy print or to download
Properties of Common Gemstones
Natural and Simulated Diamonds
Resources and Citations
- Encyclopedia Britannica, http://www.britannica.com Comment: "gemstone." Accessed 10 Nov. 2004 .
- C.W.Chesterman, K.E.Lowe, Audubon Society Field Guide to North American Rocks and Minerals, Alfred A. Knopf, New York, 1979
- The Dictionary of Art, Grove's Dictionaries Inc., New York, 1996 Comment: Gems: cutting. by Ken Scaratt
- Wikipedia: http://en.wikipedia.org/wiki/Gemstone (Accessed Nov. 2, 2005)