Turquoise is among the world’s most ancient gemstones, with records indicating it has been used since 4000 BC. Archaeological excavations revealed turquoise buried in Ancient Egyptian tombs (Ancient Egyptians called turquoise ‘Mefkat’ which also means ‘joy’ and ‘delight’), and Chinese artisans were carving it more than 3000 years ago. In 1519, Montezuma, ruler of the Aztec empire, thinking Cortes was the god Quetzalcoatl, presented him the god’s favourite gem: turquoise.
The name ‘turquoise’ comes from the French expression ‘pierre tourques’ or ‘Turkish stone’. The name appeared in the 13th Century and reflects the fact that this material likely arrived in Europe from Turkey.
Turquoise is found in only a few places on earth; arid regions where acidic, copper-rich groundwater seeps into the ground and reacts with minerals that contain phosphorous and aluminium. The result of this sedimentary process is a porous, semi-translucent to opaque compound of hydrated copper and aluminium phosphate. There are only three regions that produce turquoise in the world; Iran is widely known as the source of the most beautiful gems, with stones also originating from the Northwest of China and the Southwest of the United States.
Natural turquoise with a vibrant colour and sufficient hardness to allow for cutting and polishing is rare and highly prized. (Turquoise is quite a soft gemstone: 5 to 6 on Mohs hardness scale.) Turquoise owes its texture to its structure. It is an aggregate of microscopic crystals that forms a solid mass; the more closely together the crystals are packed, the less porous the material will be, resulting in a finer texture which reveals a beautiful, waxy lustre once polished, with higher durability.
Turquoise might lack the sparkle and clarity of gemstones like sapphires, emeralds and rubies, but their historic background and vibrant, opaque hue make them desirable gems. While stones can vary in hues and brightness, the legendary source for the top colour, sometimes described as ‘Robin’s-egg blue’, is from the Nishapur district of Iran, formerly known as Persia. This beautiful colour is often referred to as ‘Persian Blue’, whether or not it was actually mined in Iran.
The presence of a matrix may lower the value of turquoise, though well-balanced patterns are preferred by some collectors. ‘Spiderweb Turquoise’ for example, contains thin, delicate, web-like patterns providing a dark contrast to the gem’s bright blue. In the market for top quality turquoise, stones with no matrix at all will fetch the highest prices.
Turquoise has inspired designers throughout history to create elegant jewellery; often cut into cabochons. The smoothly rounded dome shape sets off turquoise’s colour, texture and any matrix beautifully. In addition, artisans fashion turquoise into round or oblong beads for strand necklaces, and into inlays. Some top colour blue turquoise is engraved with Persian or Arabic inscriptions, inlaid with gold.
Leonard Joel’s upcoming September Fine Jewels & Timepieces presents some beautiful turquoise pieces, with stones regularly offered through our weekly Jewellery Salon as well.