Gemstone

== 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 	Mineral 	Gem 	Gem 	Color 	Color 	Mohs hardness	Mohs hardness	Specific gravity	Specific gravity	Refractive index 	Refractive index 	Crystal system 	Crystal system 	Other 	Other 	Fluorescence 	Fluorescence 	Dispersion	Dispersion	Inclusions 	Inclusions
beryl 	beryl 	aquamarine 	aquamarine 	sky blue 	sky blue 	7.5-8.0 	7.5-8.0 	2.68-2.71 	2.68-2.71 	epsilon = 1.570-1.580 omega = 1.574-1.586 	epsilon = 1.570-1.580 omega = 1.574-1.586 	hexagonal crystal system; conchoidal fracture 	hexagonal crystal system; conchoidal fracture 	transparent; weakly pleochroic 	transparent; weakly pleochroic 	none to weak; synthetic stones may appear opaque and dull red in longwave UV 	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	Aquamarines are often flawless; Other contain many inclusions such as mica, pyrite and calcite
beryl 	beryl 	goshenite 	goshenite 	colorless 	colorless 	7.5-8.0 	7.5-8.0 	2.68-2.71 	2.68-2.71 	epsilon = 1.570-1.580 omega = 1.574-1.586 	epsilon = 1.570-1.580 omega = 1.574-1.586 	hexagonal crystal system; conchoidal fracture 	hexagonal crystal system; conchoidal fracture 	transparent; weakly pleochroic 	transparent; weakly pleochroic 	none to weak; synthetic stones may appear opaque and dull red in longwave UV 	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	Aquamarines are often flawless; Other contain many inclusions such as mica, pyrite and calcite
beryl 	beryl 	heliodor 	heliodor 	yellow 	yellow 	7.5-8.0 	7.5-8.0 	2.68-2.71 	2.68-2.71 	epsilon = 1.570-1.580 omega = 1.574-1.586 	epsilon = 1.570-1.580 omega = 1.574-1.586 	hexagonal crystal system; conchoidal fracture 	hexagonal crystal system; conchoidal fracture 	transparent; weakly pleochroic 	transparent; weakly pleochroic 	none to weak; synthetic stones may appear opaque and dull red in longwave UV 	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	Aquamarines are often flawless; Other contain many inclusions such as mica, pyrite and calcite
beryl 	beryl 	emerald 	emerald 	green 	green 	7.5-8.0 	7.5-8.0 	2.68-2.78 	2.68-2.78 	epsilon = 1.571-1.581 omega = 1.577-1.588 	epsilon = 1.571-1.581 omega = 1.577-1.588 	hexagonal crystal system; conchoidal fracture 	hexagonal crystal system; conchoidal fracture 	transparent; weakly pleochroic 	transparent; weakly pleochroic 	none to weak; synthetic stones may appear opaque and dull red in longwave UV 	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	Aquamarines are often flawless; Other contain many inclusions such as mica, pyrite and calcite
beryl 	beryl 	morganite 	morganite 	pink 	pink 	7.5-8.0 	7.5-8.0 	2.66-2.83 	2.66-2.83 	epsilon = 1.580-1.590 omega = 1.589-1.601 	epsilon = 1.580-1.590 omega = 1.589-1.601 	hexagonal crystal system; conchoidal fracture 	hexagonal crystal system; conchoidal fracture 	transparent; weakly pleochroic 	transparent; weakly pleochroic 	none to weak; synthetic stones may appear opaque and dull red in longwave UV 	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	Aquamarines are often flawless; Other contain many inclusions such as mica, pyrite and calcite
chrysoberyl 	chrysoberyl 	alexandrite 	alexandrite 	green in daylight, red in incandescent light 	green in daylight, red in incandescent light 	8.5 	8.5 	3.5-3.8 	3.5-3.8 	alpha = 1.745 beta = 1.748 gamma = 1.754 	alpha = 1.745 beta = 1.748 gamma = 1.754 	orthorhombic, flattened crystals, often twinned 	orthorhombic, flattened crystals, often twinned 	transparent; chrysoberyl cat's-eye is chatoyant 	transparent; chrysoberyl cat's-eye is chatoyant 	strongly pleochroic 	strongly pleochroic 	d = 0.015 	d = 0.015 	 	
cristobalite 	cristobalite 	opal 	opal 	milky white to colorless;; variable pale shades 	milky white to colorless;; variable pale shades 	5.5-6.5 	5.5-6.5 	1.98-2.25 	1.98-2.25 	1.435-1.455 	1.435-1.455 	tetragonal submicrocrystalline aggregates; irregular concretions; glass- like fracture 	tetragonal submicrocrystalline aggregates; irregular concretions; glass- like fracture 	opaque; contains some water causing the physical properties to vary 	opaque; contains some water causing the physical properties to vary 	may fluoresce white or pale green; may phosphoresce 	may fluoresce white or pale green; may phosphoresce 	 	 	possible 	possible
corundum 	corundum 	sapphire 	sapphire 	blue 	blue 	9.0 	9.0 	4.0 	4.0 	epsilon = 1.757-1.768 omega = 1.765-1.776 	epsilon = 1.757-1.768 omega = 1.765-1.776 	hexagonal; conchoidal fracture 	hexagonal; conchoidal fracture 	transparent; marked dichroism 	transparent; marked dichroism 	orange to red; heat treated stones may fluoresce green 	orange to red; heat treated stones may fluoresce green 	d = 0.018 	d = 0.018 	many including minerals (rutile), fluids, angular banding 	many including minerals (rutile), fluids, angular banding
corundum 	corundum 	ruby 	ruby 	red 	red 	9.0 	9.0 	4.0 	4.0 	epsilon = 1.757-1.768 omega = 1.765-1.776 	epsilon = 1.757-1.768 omega = 1.765-1.776 	hexagonal; conchoidal fracture 	hexagonal; conchoidal fracture 	transparent; marked dichroism 	transparent; marked dichroism 	orange to red; heat treated stones may fluoresce green 	orange to red; heat treated stones may fluoresce green 	d = 0.018 	d = 0.018 	many including minerals (rutile), fluids, angular banding 	many including minerals (rutile), fluids, angular banding
corundum 	corundum 	padmaradschah 	padmaradschah 	orange 	orange 	9.0 	9.0 	4.0 	4.0 	epsilon = 1.757-1.768 omega = 1.765-1.776 	epsilon = 1.757-1.768 omega = 1.765-1.776 	hexagonal; conchoidal fracture 	hexagonal; conchoidal fracture 	transparent; marked dichroism 	transparent; marked dichroism 	orange to red; heat treated stones may fluoresce green 	orange to red; heat treated stones may fluoresce green 	d = 0.018 	d = 0.018 	many including minerals (rutile), fluids, angular banding 	many including minerals (rutile), fluids, angular banding
diamond 	diamond 	diamond 	diamond 	variable (colorless, yellow, blue) 	variable (colorless, yellow, blue) 	10.0 	10.0 	3.52 	3.52 	2.4175 	2.4175 	isometric flattened octahedrons; dodecahedrons 	isometric flattened octahedrons; dodecahedrons 	transparent; perfect cleavage in four directions 	transparent; perfect cleavage in four directions 	may fluoresce pale colors in longwave UV; may phosphoresce 	may fluoresce pale colors in longwave UV; may phosphoresce 	d = 0.044 	d = 0.044 	trigonal on surface; numerous inclusions 	trigonal on surface; numerous inclusions
potash feldspar 	potash feldspar 	orthoclase 	orthoclase 	pale yellow to flesh red 	pale yellow to flesh red 	6.0-6.5 	6.0-6.5 	2.6 	2.6 	alpha = 1.518 beta = 1.522 gamma = 1.522 	alpha = 1.518 beta = 1.522 gamma = 1.522 	monoclinic crystals 	monoclinic crystals 	two perfect cleavages at right angles 	two perfect cleavages at right angles 	 	 	 	 	 	
potash feldspar 	potash feldspar 	moonstone 	moonstone 	colorless, white to yellowish 	colorless, white to yellowish 	6.0-6.5 	6.0-6.5 	2.6 	2.6 	alpha = 1.518 beta = 1.522 gamma = 1.522 	alpha = 1.518 beta = 1.522 gamma = 1.522 	nodules or masses 	nodules or masses 	blue opalecsence 	blue opalecsence 	 	 	 	 	 	
potash feldspar 	potash feldspar 	amazonite 	amazonite 	yellow green to blue green 	yellow green to blue green 	6.0-6.5 	6.0-6.5 	2.6 	2.6 	alpha = 1.518 beta = 1.522 gamma = 1.522 	alpha = 1.518 beta = 1.522 gamma = 1.522 	triclinic, large crystals 	triclinic, large crystals 	variety of microcline 	variety of microcline 	 	 	 	 	 	
plagioclase feldspar	plagioclase feldspar	sunstone (aventurine) 	sunstone (aventurine) 	colorless to pale pink 	colorless to pale pink 	6.0-6.5 	6.0-6.5 	2.6-2.7 	2.6-2.7 	alpha = 1.527-1.577 beta=1.531-1.585 gamma = 1.538-1.590 	alpha = 1.527-1.577 beta=1.531-1.585 gamma = 1.538-1.590 	triclinic prismatic crystals; two perfect cleavages at right angles 	triclinic prismatic crystals; two perfect cleavages at right angles 	transparent to opaque; iridescent; 	transparent to opaque; iridescent; 	 	 	 	 	inclusions give spangled appearance 	inclusions give spangled appearance
plagioclase feldspar	plagioclase feldspar	labradorite 	labradorite 	grayish shades 	grayish shades 	6.0-6.5 	6.0-6.5 	2.6-2.7 	2.6-2.7 	alpha = 1.527-1.577 beta=1.531-1.585 gamma = 1.538-1.590 	alpha = 1.527-1.577 beta=1.531-1.585 gamma = 1.538-1.590 	triclinic prismatic crystals; two perfect cleavages at right angles 	triclinic prismatic crystals; two perfect cleavages at right angles 	transparent to opaque; iridescent; 	transparent to opaque; iridescent; 	 	 	 	 	 	
fluorite 	fluorite 	fluorite 	fluorite 	lavender to green 	lavender to green 	 	 	 	 	1.434 	1.434 	conchoidal fracture 	conchoidal fracture 	transparent 	transparent 	strong 	strong 	 	 	color zoning 	color zoning
garnet 	garnet 	almandine (carbuncle) 	almandine (carbuncle) 	deep red with a trace of purple 	deep red with a trace of purple 	7.0-7.5 	7.0-7.5 	4.3 	4.3 	1.79-1.83 	1.79-1.83 	isometric euhedral crystals, with dodecahedrons and trapezodrons most common; conchoidal fracture	isometric euhedral crystals, with dodecahedrons and trapezodrons most common; conchoidal fracture	light colored varieties are transparent; no birefringence, no pleochroism	light colored varieties are transparent; no birefringence, no pleochroism	none 	none 	d = 0.024 	d = 0.024 	needles; single and multiphase prisms 	needles; single and multiphase prisms
garnet 	garnet 	andradite (Uralian emerald) 	andradite (Uralian emerald) 	deep emerald-green 	deep emerald-green 	6.5-7.0 	6.5-7.0 	3.9 	3.9 	1.887 	1.887 	isometric euhedral crystals, with dodecahedrons and trapezodrons most common; conchoidal fracture	isometric euhedral crystals, with dodecahedrons and trapezodrons most common; conchoidal fracture	light colored varieties are transparent; no birefringence, no pleochroism	light colored varieties are transparent; no birefringence, no pleochroism	none 	none 	d = 0.057 	d = 0.057 	needles; single and multiphase prisms 	needles; single and multiphase prisms
garnet 	garnet 	grossularite (hessonite) 	grossularite (hessonite) 	yellow-brown to orange, red, or green 	yellow-brown to orange, red, or green 	7.0-7.5 	7.0-7.5 	3.6 	3.6 	1.734-1.740 	1.734-1.740 	isometric euhedral crystals, with dodecahedrons and trapezodrons most common; conchoidal fracture	isometric euhedral crystals, with dodecahedrons and trapezodrons most common; conchoidal fracture	light colored varieties are transparent; no birefringence, no pleochroism	light colored varieties are transparent; no birefringence, no pleochroism	pale orange in long UV; yellow in short UV 	pale orange in long UV; yellow in short UV 	d = 0.028 	d = 0.028 	needles; single and multiphase prisms 	needles; single and multiphase prisms
garnet 	garnet 	pyrope 	pyrope 	dark blood red 	dark blood red 	7.0-7.5 	7.0-7.5 	3.78 	3.78 	1.714-1.742 	1.714-1.742 	isometric euhedral crystals, with dodecahedrons and trapezodrons most common; conchoidal fracture	isometric euhedral crystals, with dodecahedrons and trapezodrons most common; conchoidal fracture	light colored varieties are transparent; no birefringence, no pleochroism	light colored varieties are transparent; no birefringence, no pleochroism	none 	none 	d = 0.027 	d = 0.027 	needles; single and multiphase prisms 	needles; single and multiphase prisms
garnet 	garnet 	spessartine 	spessartine 	yellow-orange to brown- red 	yellow-orange to brown- red 	7.0-7.5 	7.0-7.5 	4.15 	4.15 	1.800-1.810 	1.800-1.810 	isometric euhedral crystals, with dodecahedrons and trapezodrons most common; conchoidal fracture	isometric euhedral crystals, with dodecahedrons and trapezodrons most common; conchoidal fracture	light colored varieties are transparent; no birefringence, no pleochroism	light colored varieties are transparent; no birefringence, no pleochroism	none 	none 	d = 0.027 	d = 0.027 	needles; single and multiphase prisms 	needles; single and multiphase prisms
jade 	jade 	jadeite (Imperial jade) 	jadeite (Imperial jade) 	green but may be white, black, red, brown, yellow, blue or mauve 	green but may be white, black, red, brown, yellow, blue or mauve 	6.0 	6.0 	3.33-3.34 	3.33-3.34 	alpha = 1.640-1.658 beta=1.645-1.663 gamma = 1.652-1.673 	alpha = 1.640-1.658 beta=1.645-1.663 gamma = 1.652-1.673 	monoclinic compact or fibrous masses; granular to splintery fracture 	monoclinic compact or fibrous masses; granular to splintery fracture 	translucent to opaque; greasy luster 	translucent to opaque; greasy luster 	may have pale white color in long UV light 	may have pale white color in long UV light 	 	 	 	
jade 	jade 	nephrite 	nephrite 	deep spinach green to near-white 	deep spinach green to near-white 	6.0-6.5 	6.0-6.5 	2.96-3.02 	2.96-3.02 	alpha = 1.600-1.672 beta=1.614-1.686 gamma = 1.627-1.693 	alpha = 1.600-1.672 beta=1.614-1.686 gamma = 1.627-1.693 	monoclinic compact masses; conchoidal to granular fracture 	monoclinic compact masses; conchoidal to granular fracture 	translucent to opaque; greasy or waxy appearance 	translucent to opaque; greasy or waxy appearance 	none 	none 	 	 	some dark inclusions 	some dark inclusions
lazurite 	lazurite 	lapis lazuli 	lapis lazuli 	azure blue with flecks of white and gold 	azure blue with flecks of white and gold 	5.0-5.5 	5.0-5.5 	2.7-2.9 	2.7-2.9 	1.50-1.67 	1.50-1.67 	isometric with compact masses; opaque 	isometric with compact masses; opaque 	decomposed by hydrochloric acid 	decomposed by hydrochloric acid 	 	 	 	 	 	
olivine 	olivine 	peridot; chrysolite 	peridot; chrysolite 	yellow green; dark bottle green; olive green 	yellow green; dark bottle green; olive green 	6.5-7.0 	6.5-7.0 	3.3-3.4 	3.3-3.4 	alpha = 1.635-1.671 beta = 1.652-1.698 gamma = 1.671-1.707	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 	orthorhombic system with massive or granular forms; fracture=uneven to conchoidal 	transparent 	transparent 	 	 	d = 0.020 	d = 0.020 	 	
quartz 	quartz 	amethyst 	amethyst 	purple 	purple 	7.0 	7.0 	2.65 	2.65 	epsilon = 1.553 omega = 1.544 	epsilon = 1.553 omega = 1.544 	conchoidal fracture 	conchoidal fracture 	transparent; heat treatment may bleach stones 	transparent; heat treatment may bleach stones 	 	 	d = 0.013 	d = 0.013 	 	
quartz 	quartz 	cairngorm (smoky quartz) 	cairngorm (smoky quartz) 	smoky brown 	smoky brown 	7.0 	7.0 	2.65 	2.65 	epsilon = 1.553 omega = 1.544 	epsilon = 1.553 omega = 1.544 	conchoidal fracture 	conchoidal fracture 	transparent; heat treatment may bleach stones 	transparent; heat treatment may bleach stones 	 	 	 	 	 	
quartz 	quartz 	citrine 	citrine 	yellow 	yellow 	7.0 	7.0 	2.65 	2.65 	epsilon = 1.553 omega = 1.544 	epsilon = 1.553 omega = 1.544 	conchoidal fracture 	conchoidal fracture 	transparent; heat treatment may bleach stones 	transparent; heat treatment may bleach stones 	 	 	 	 	 	
quartz 	quartz 	rock crystal 	rock crystal 	colorless 	colorless 	7.0 	7.0 	2.65 	2.65 	epsilon = 1.553 omega = 1.544 	epsilon = 1.553 omega = 1.544 	conchoidal fracture 	conchoidal fracture 	transparent; heat treatment may bleach stones 	transparent; heat treatment may bleach stones 	 	 	 	 	 	
quartz 	quartz 	rose quartz 	rose quartz 	pink 	pink 	7.0 	7.0 	2.65 	2.65 	epsilon = 1.553 omega = 1.544 	epsilon = 1.553 omega = 1.544 	conchoidal fracture 	conchoidal fracture 	transparent; heat treatment may bleach stones 	transparent; heat treatment may bleach stones 	 	 	 	 	 	
quartz 	quartz 	agate (moss agate, mocha stone) 	agate (moss agate, mocha stone) 	variable 	variable 	7.0 	7.0 	2.65 	2.65 	epsilon = 1.553 omega = 1.544 	epsilon = 1.553 omega = 1.544 	compact masses; nodules 	compact masses; nodules 	translucent to opaque 	translucent to opaque 	 	 	 	 	 	
quartz 	quartz 	chalcedony (onyx, carnelian, sardonyx, chrysoprase, bloodstone, heliotrope)	chalcedony (onyx, carnelian, sardonyx, chrysoprase, bloodstone, heliotrope)	variable 	variable 	7.0 	7.0 	2.65 	2.65 	epsilon = 1.553 omega = 1.544 	epsilon = 1.553 omega = 1.544 	compact masses; nodules 	compact masses; nodules 	translucent to opaque 	translucent to opaque 	 	 	 	 	 	
quartz 	quartz 	jasper 	jasper 	variable 	variable 	7.0 	7.0 	2.65 	2.65 	epsilon = 1.553 omega = 1.544 	epsilon = 1.553 omega = 1.544 	compact masses; nodules 	compact masses; nodules 	translucent to opaque 	translucent to opaque 	 	 	 	 	 	
spinel 	spinel 	Balas ruby; 	Balas ruby; 	typically red; also variable: yellow (rubicelle), violet (almandine), pleonast (blue, black), gahnite (blue-green)	typically red; also variable: yellow (rubicelle), violet (almandine), pleonast (blue, black), gahnite (blue-green)	8 	8 	3.6 	3.6 	1.715-1.725 	1.715-1.725 	isometric octahedral crystals; rounded grains; conchoidal fracture 	isometric octahedral crystals; rounded grains; conchoidal fracture 	transparent 	transparent 	natural fluoresces red in longwave UV; synthetic may show colors in shortwave UV	natural fluoresces red in longwave UV; synthetic may show colors in shortwave UV	d = 0.020 	d = 0.020 	fingerprint pattern inclusions 	fingerprint pattern inclusions
topaz 	topaz 	topaz, hyacinth 	topaz, hyacinth 	yellow, green, blue, violet or red 	yellow, green, blue, violet or red 	8 	8 	3.4-3.6 	3.4-3.6 	alpha = 1.606-1.629 beta = .609-1.631 gamma = 1.616-1.638 	alpha = 1.606-1.629 beta = .609-1.631 gamma = 1.616-1.638 	orthorhombic prismatic crystals; perfect cleavage in one direction 	orthorhombic prismatic crystals; perfect cleavage in one direction 	transparent; highly pleochroic; turns soft red when heated 	transparent; highly pleochroic; turns soft red when heated 	may fluoresce yellow in longwave UV 	may fluoresce yellow in longwave UV 	d = 0.014 	d = 0.014 	single and multiphase 	single and multiphase
tourmaline 	tourmaline 	achroite 	achroite 	colorless or green 	colorless or green 	7-7.5 	7-7.5 	2.9-3.2 	2.9-3.2 	epsilon = 1.610-1.650 omega = 1.635-1.675 	epsilon = 1.610-1.650 omega = 1.635-1.675 	hexagonal prismatic crystals, often rounded or oval; conchoidal fracture 	hexagonal prismatic crystals, often rounded or oval; conchoidal fracture 	transparent; pleochroic 	transparent; pleochroic 	none to weak 	none to weak 	d = 0.016 	d = 0.016 	gas and liquid pockets with color zoning 	gas and liquid pockets with color zoning
tourmaline 	tourmaline 	dravite 	dravite 	brown 	brown 	7-7.5 	7-7.5 	2.9-3.2 	2.9-3.2 	epsilon = 1.610-1.650 omega = 1.635-1.675 	epsilon = 1.610-1.650 omega = 1.635-1.675 	hexagonal prismatic crystals, often rounded or oval; conchoidal fracture 	hexagonal prismatic crystals, often rounded or oval; conchoidal fracture 	transparent; pleochroic 	transparent; pleochroic 	none to weak 	none to weak 	d = 0.016 	d = 0.016 	gas and liquid pockets with color zoning 	gas and liquid pockets with color zoning
tourmaline 	tourmaline 	indicolite 	indicolite 	blue 	blue 	7-7.5 	7-7.5 	2.9-3.2 	2.9-3.2 	epsilon = 1.610-1.650 omega = 1.635-1.675 	epsilon = 1.610-1.650 omega = 1.635-1.675 	hexagonal prismatic crystals, often rounded or oval; conchoidal fracture 	hexagonal prismatic crystals, often rounded or oval; conchoidal fracture 	transparent; pleochroic 	transparent; pleochroic 	none to weak 	none to weak 	d = 0.016 	d = 0.016 	gas and liquid pockets with color zoning 	gas and liquid pockets with color zoning
tourmaline 	tourmaline 	rubellite 	rubellite 	pink 	pink 	7-7.5 	7-7.5 	2.9-3.2 	2.9-3.2 	epsilon = 1.610-1.650 omega = 1.635-1.675 	epsilon = 1.610-1.650 omega = 1.635-1.675 	hexagonal prismatic crystals, often rounded or oval; conchoidal fracture 	hexagonal prismatic crystals, often rounded or oval; conchoidal fracture 	transparent; pleochroic 	transparent; pleochroic 	none to weak 	none to weak 	d = 0.016 	d = 0.016 	gas and liquid pockets with color zoning 	gas and liquid pockets with color zoning
tourmaline 	tourmaline 	schorl 	schorl 	black 	black 	7-7.5 	7-7.5 	2.9-3.2 	2.9-3.2 	epsilon = 1.610-1.650 omega = 1.635-1.675 	epsilon = 1.610-1.650 omega = 1.635-1.675 	hexagonal prismatic crystals, often rounded or oval; conchoidal fracture 	hexagonal prismatic crystals, often rounded or oval; conchoidal fracture 	transparent; pleochroic 	transparent; pleochroic 	none to weak 	none to weak 	d = 0.016 	d = 0.016 	gas and liquid pockets with color zoning 	gas and liquid pockets with color zoning
tourmaline 	tourmaline 	siberite 	siberite 	violet 	violet 	7-7.5 	7-7.5 	2.9-3.2 	2.9-3.2 	epsilon = 1.610-1.650 omega = 1.635-1.675 	epsilon = 1.610-1.650 omega = 1.635-1.675 	hexagonal prismatic crystals, often rounded or oval; conchoidal fracture 	hexagonal prismatic crystals, often rounded or oval; conchoidal fracture 	transparent; pleochroic 	transparent; pleochroic 	none to weak 	none to weak 	d = 0.016 	d = 0.016 	gas and liquid pockets with color zoning 	gas and liquid pockets with color zoning
turquoise 	turquoise 	turquoise 	turquoise 	blue to greenish-blue 	blue to greenish-blue 	5.0-6.0 	5.0-6.0 	2.6-2.9 	2.6-2.9 	alpha = 1.61 beta = 1.62 gamma = 1.65 	alpha = 1.61 beta = 1.62 gamma = 1.65 	cryptocrystalline to fine granular; fracture=conchoidal 	cryptocrystalline to fine granular; fracture=conchoidal 	opaque; color fades in sunlight 	opaque; color fades in sunlight 	 	 	 	 	 	
zircon 	zircon 	jargon 	jargon 	variable 	variable 	6.0-7.5 	6.0-7.5 	4.6-4.7 	4.6-4.7 	epsilon = 1.968-2.015 omega = 1.923-1.960 	epsilon = 1.968-2.015 omega = 1.923-1.960 	tetragonal system with square prismatic crystals; fracture=uneven 	tetragonal system with square prismatic crystals; fracture=uneven 	transparent; pleochroic 	transparent; pleochroic 	some show dull yellow color; some may phosphoresce 	some show dull yellow color; some may phosphoresce 	d = 0.048 	d = 0.048 	rutile crystals; single and multiphase 	rutile crystals; single and multiphase
zircon 	zircon 	Matura diamond 	Matura diamond 	colorless 	colorless 	6.0-7.5 	6.0-7.5 	4.6-4.7 	4.6-4.7 	epsilon = 1.968-2.015 omega = 1.923-1.960 	epsilon = 1.968-2.015 omega = 1.923-1.960 	tetragonal system with square prismatic crystals; fracture=uneven 	tetragonal system with square prismatic crystals; fracture=uneven 	transparent; pleochroic 	transparent; pleochroic 	some show dull yellow color; some may phosphoresce 	some show dull yellow color; some may phosphoresce 	d = 0.048 	d = 0.048 	rutile crystals; single and multiphase 	rutile crystals; single and multiphase
zircon 	zircon 	hyacinth 	hyacinth 	yellow orange 	yellow orange 	6.0-7.5 	6.0-7.5 	4.6-4.7 	4.6-4.7 	epsilon = 1.968-2.015 omega = 1.923-1.960 	epsilon = 1.968-2.015 omega = 1.923-1.960 	tetragonal system with square prismatic crystals; fracture=uneven 	tetragonal system with square prismatic crystals; fracture=uneven 	transparent; pleochroic 	transparent; pleochroic 	some show dull yellow color; some may phosphoresce 	some show dull yellow color; some may phosphoresce 	d = 0.048 	d = 0.048 	rutile crystals; single and multiphase 	rutile crystals; single and multiphase
zircon 	zircon 	jacinth 	jacinth 	red brown 	red brown 	6.0-7.5 	6.0-7.5 	4.6-4.7 	4.6-4.7 	epsilon = 1.968-2.015 omega = 1.923-1.960 	epsilon = 1.968-2.015 omega = 1.923-1.960 	tetragonal system with square prismatic crystals; fracture=uneven 	tetragonal system with square prismatic crystals; fracture=uneven 	transparent; pleochroic 	transparent; pleochroic 	some show dull yellow color; some may phosphoresce 	some show dull yellow color; some may phosphoresce 	d = 0.048 	d = 0.048 	rutile crystals; single and multiphase 	rutile crystals; single and multiphase
== 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 ==
==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)
Category:Materials database