Blue Sapphire Gemstone 18K White Gold Plated Ring Size 6 Sapphires are precious gemstones formed from a mineral called corundum. Blue Sapphires get their color from titanium and iron trace elements. Blue Sapphire rates 9 out of 10 on the Mohs scale of mineral hardness, so it is a very durable gem. The word 'sapphire' comes from the Greek word "sappheiros," which means blue. Sapphire, particularly the deep blue variety, has been associated with royalty for centuries. Medieval kings wore sapphires, believing the gems would protect them in battle.