the.com/corundum
the second-hardest mineral on Earth, moonlighting as both ruby and sapphire.
means Corundum is a crystalline form of aluminum oxide, an extremely hard mineral whose colored varieties are prized as gemstones — red ones as ruby, all others as sapphire.
from The name comes, by way of Anglo-Indian usage, from Tamil and the related Dravidian languages — kurundam — which is itself thought to trace back to Sanskrit kuruvinda, meaning ruby. So a word for the hardest of common gems traveled from Sanskrit through southern India into English mineralogy, carrying its red stone with it.
- same rock
- Rubies and sapphires are identical, just colored differently
- hardness
- Ranks 9 on Mohs, beaten only by diamond
- the color trick
- Chromium makes red, iron and titanium make blue
- sandpaper job
- Crushed into emery for industrial abrasives and grinding
- melting point
- Endures over 2000 degrees Celsius before liquefying
burmese ruby — world's most valuable corundum variety, mined in myanmar, priced at $10,000+ per carat
kashmir sapphire — legendary blue corundum from kashmir region, valued at $5,000-12,000 per carat since the 19th century
mogok valley rubies — myanmar's primary ruby deposit producing vivid red corundum known as 'pigeon's blood' rubies