Learn · Gemstones and pearls
Where gems come from
Pick a gem to light up the countries that mine it, from the main sources today to the historic ones, with the key mining areas marked. Switch on the trade centres to see where rough is bought, cut and sold.
Pick a gem to light up the countries that mine it; switch on the trading and cutting centres.
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Hue, tone and saturation
How the trade describes a coloured stone's colour: hue, tone and saturation
Birthstones around the world
Every month on the American, British, Japanese and nine-gem lists
The 7 pearl value factors
GIA's seven pearl value factors, changed one at a time on one pearl
Gem treatments explained
Usual treatments gem by gem, the trade codes, care and disclosure rules
Cutting angles and light
Change a stone's cutting angles and follow the light: where it returns and where it leaks Preview