Gemstone Knowledge Center
Gem profiles, cut diagrams and resources for gemstone enthusiasts
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Gem Radioactivity
Safety, identification, treatment detection
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Safety Guide
Traditional Precious Stones
Diamond, Sapphire, Ruby, Emerald
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Distinctive Gemstones
Opal, Spinel, Tanzanite, Tourmaline, Garnet, Zircon
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Fine Stones & Crystals
Amethyst, Aquamarine, Citrine, Peridot, Quartz, Topaz
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Traditional Precious Stones
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Diamond
Ruby
Sapphire
Emerald
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Opal
Garnet
Distinctive Gemstones
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Spinel
Zircon
Tanzanite
Malachite
Tourmaline
Moonstone
Fine Stones & Crystals
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Amethyst
Aquamarine
Citrine
Peridot
Quartz
Topaz
Additional Resources
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Pearl
Organic Gems
Pearl, Amber, Coral, Mother of Pearl, Jet
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View guides ›
View guides ›
Rare Gems & Varieties
Alexandrite, Padparadscha, Paraíba, Tsavorite and exceptional varieties
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View rare varieties ›
Gem Classification
Classification systems by transparency, tone, saturation and color
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Lapidary Cut Diagrams
Classic cuts: round brilliant, oval, cushion, pear, emerald, marquise
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View guides ›
Classification Guides
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Clarity
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Tone
Cut Diagrams
Color
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Round Brilliant
Pear
Oval
Emerald
Cushion
Marquise
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