December has three gemstones – zircon, tanzanite and turquoise. I am going to talk about the first two gemstones in this post and deal with turquoise in a following post.

Zircons are a very underrated gemstone. They have high refraction which means that they reflect a lot of light and and so show sparkles and fire. White or colourless zircons were often used as diamond substitutes They range in colour from shades of of brown, yellow, blue, green and colourless. The gem is heat treated, particularly to produce intense blue colours, but for other colours as well.

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Zircon ring

Zircon is an old gemstone, both in creation and its our use of it in jewellery. Zircons are one of the oldest minerals ever found, some examples being dated as being over 4 billion years ago. They are created through crystalisation of magna and are extremely durable. It has been used in jewellery for 1000s of years under various names, such as jargoon, and hyacinth or jacinth. Pliny is thought to have called it chrysolithos, describing it as a yellow stone. The name ‘zircon’ was derived from either Arabic or Persian words around 1783.

Despite the similarity in name, zircons shouldn’t be confused with cubic zirconia as the latter is a manmade gemstone and does not occur as a natural stone.

Tanzanite is a member of the Zoisite family of  minerals and a deposit was only discovered gemstones in Tanzania in 1967. Tiffany’s bought the rights to sole distribution and Henry B Platt, Tiffany’s Chair at the time, named the new gemstone ‘Tanzanite’. The  firm promoted the stone extensively and managed to get it accepted a the third gemstone for December

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Tanzanite ring with diamond set shoulders

Next post: turquoise.