Gem Library, Jewellery, Jewelry, Sri Lanka, Travel

Weekend brunch #9: Red, White & Blue (Corundum)

Happy Fourth of July to our American friends and all who celebrate!
To mark this occasion, today’s weekend brunch is dedicated to all things red, white and blue. Perhaps the heading is somewhat misleading, as corundum is usually red (ruby), grey (rather than white, sapphire) and of course the famous rich-blue high grade sapphire of Sri Lanka, Burma (Myanmar) and India. The variation of colour lends itself to iron and titanium impurities.

Photograph of the Star of Bombay sapphire. Smithsonian Institute.  Photo (c) Chip Clark
Photograph of the Star of Bombay sapphire. Smithsonian Institute.
Photo (c) Chip Clark.

The most valuable sapphire is clear and deep blue, and the thicker/closer the rutile (mineral) needles are inside, the more the chatoyancy of the star is highlighted. The Lapidary (“Cutter”) cuts the gems en cabochon, to take advantage of and display the best asterism. Due to its hardness (nine) corundum can be fashioned into everyday pieces of jewellery. Ideally it is worth purchasing loose stones for rings or ready-made rings, as the star stands out in a beautiful visible display beneath direct light.
Thailand is to corundum what Silicon Valley is to the Tech World. Hundreds of cutting hubs in Thailand produce the best effect (asterism) in corundum. Overall, we’d recommend Sri Lanks for large loose stones (even better if you can get to the mine source), and Thailand for finely cut craftsmanship.

Harlow 85ct star sapphire
Harlow and an 85 carat star sapphire

If you’re in The Hamptons for the weekend (hurrah for making it through traffic on Thursday), perhaps indulging in much needed relaxation, or your annual family get together – whatever you do have a fabulous weekend!