https://www.oravagems.com/
Orava (Private) Limited | Coloured Gemstones for Watches and Jewellery
Founded in 2006, Orava (Private) Limited caters to the intricate needs of the fine jewelry and watch sectors. Orava precision-cuts colored gemstones serving...
private limitedcoloured gemstonesfor watchesoravajewellery
https://www.gemearth.com/
GemEarth Precious & Semi-Precious Coloured Gemstones
Gem Earth offers precious gemstones (ruby, sapphire, emerald) and semi-precious gems (spinel, tourmaline, tanzanite, garnet, topaz, peridot, opal, amethyst,)
precioussemicolouredgemstones
https://www.gemmolog-gems.com/
Gemmolog Gems | coloured gemstones
Coloured gemstones from a well trained gemmologist, precise faceting, tailored gemstone courses
gemscoloured
https://www.christies.com/en/stories/coloured-stones-collecting-guide-37d7d9f70f2942c88abba3fd56aab4a3
A collecting guide to coloured diamonds and gemstones | Christie's
From rubies and emeralds to rare coloured diamonds, an expert guide for buyers seeking coloured gemstones for their collection
diamonds and gemstonescollecting guidecolouredchristie