The Specimen Library / Record
Corundum / Ruby & Sapphire
Aluminum oxide / mineral species and gem varieties
Ruby and sapphire belong to one mineral species, with a much wider palette than red and blue.
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01 · The material
Natural History
Corundum forms in suitable aluminum-rich, silica-poor settings. Different deposits have different histories.
02 · Observe
Under the Loupe
Natural, synthetic, heated and other treated material can share a convincing appearance. Color is not a natural-origin test.
03 · Ownership
Collect & Care
Hardness does not remove every risk. Fractures, fillings, settings and composite construction can change appropriate cleaning.
04 · The human story
History, Lore & Tradition
Documented history
Ruby names red gem corundum; sapphire covers the other gem colors. Color boundaries and trade descriptions need care.
Sources & further reading
References are labeled by role. A source documenting a belief is not evidence of a medical or mineralogical effect. Reflection prompts are C&C editorial suggestions.
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Field resources in development
- Collector Record · future free download
- Quick Reference · future free download
- Coloring & Discovery Page · future low-cost resource
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