Birthstones: December - Turquoise, Tanzanite & Zircon
As we approach the end of the year, with the nights at their shortest and the weather chilly, we come to December’s birthstones. The year ends then with three beautiful stones for us to talk about: Turquoise, Tanzanite and Zircon.
Rough Turquoise (Source: Pinterest)
What Makes a Turquoise
Turquoise is made up of a bunch of microscopic crystals formed by copper-rich groundwater mixing with phosphorus and aluminium. It occurs in dry areas as a semi-transparent or opaque blue-green mineral found within rocks or other minerals. There are veins from the host rock or mineral called the matrix that usually covers the gemstone.
Where Turquoise is Mined
Native American Turquoise heishi jewellery (Source: Trip Savvy)
The primary sources of Turquoise is the American Southwest, namely the states of Nevada, Arizona, and New Mexico, as well as the northwestern provinces of Hubei and Shaanxi in China.
Iran, where the Persian blue variation of Turquoise comes from, is another major source of the gemstone.
Lynch Station, Virginia in the USA is the only place that produces translucent Turquoise, making this unique variation incredibly expensive.
History and Significance of Turquoise
Morenci Turquoise squash blossom necklace (Source: Two Grey Hills)
The use of Turquoise started with ancient civilisations. Egyptian royalty from as far back as 5500 BC wore them as jewellery. Chinese artisans crafted valuable pieces as early as 3000 BC.
The Persian mines of yore produced the finest Turquoise gemstones. These eventually made their way to Europe during the 1600s via French and Turkish trade routes, thus giving the mineral its modern name.
Native American tribes such as the Navajo, Hopi, Zuni, and Pueblo have long been making Turquoise jewellery, many of which were in the form of animals. These pieces are called fetishes. They also used Turquoise as amulets and for barter and ceremonies.
Rough Tanzanite (Source: Unlimited Gems)
What Makes a Tanzanite
Tanzanite is the violet-blue gemstone variety of the mineral zoisite. It exhibits trichroism, meaning it reflects three colours depending on which direction it is viewed from. Its natural state shows violet-red and yellow-green colours along with its deep blue shade.
Tanzanite is generally heat-treated to remove its trichroism. By the time it gets to market as a separate stone or part of jewellery, it only has its violet-blue colour.
Where Tanzanite is Mined
There is only one place where Tanzanite is mined, and it is the country it got its name from — Tanzania. Specifically, it is mined in Merelani Hills near the Arusha region.
History and Significance of Tanzanite
Vintage Tanzanite ring (Source: Pinterest)
Tanzanite was only discovered in 1967 by Portuguese Indian fortune hunter Manuel D’souza along Mt. Kilimanjaro. When D’souza returned to the site to begin mining operations, he brought along geologist Dr. John Saul.
Dr. John Saul and his father Hyman Saul identified the stone as a variation of the mineral Zoisite. They brought the gem to Tiffany & Co’s President Walter Hoving and its chief gem buyer Henry Platt. They decided to call it Tanzanite, after the country where it was discovered.
Golden red Zircons on biotite and hornblende matrix (Source: Gem Society)
What Makes a Zircon
Zircon gemstones are the high-quality variants of the mineral of the same name. It naturally occurs as crystals set in different kinds of rocks. The impurities a Zircon crystal contains determines its colour.
Colourless Zircon was the most widely used version when it served as a Diamond simulant in the early 20th century. Its brilliance and fire made it a convincing copy of much more expensive Diamond gemstones.
Where Zircon is Mined
Edwardian Zircon and Diamond milgrain cluster ring (Source: Pinterest)
Sri Lanka is the main source for Zircon gemstones. The country produces Zircon gems of all colours.
The other major Zircon mining locations are in Southeast Asia. Cambodia is where most Zircon of varying colours get heat-treated to become blue or colourless Zircon. In Myanmar, gemstone quality yellow and green Zircon are extracted in gem gravels with Ruby. The industry also relies on Thailand’s mines for most of its gemstone-quality Zircon.
History and Significance of Zircon
Gold Ring with Diamonds and Zircon (Source: Pinterest)
Zircon boasts of being one of the 12 gemstones worn by the high priests of Israel from the Old Testament of the Bible. The term “Zircon” is said to come from either the Arabic word “zarkun,” which means cinnabar or vermilion, or from the Persian word “zargun,” which means gold coloured.
Europeans during the Middle Ages believed a Zircon gem could ward off evil, promote prosperity, and induce restful sleep. It was also considered a symbol of wisdom and honour.
By the Victorian period, blue Zircon caught on with the English upper class, before the colourless variant became known as a cheaper imitation of Diamonds by the turn of the century. Time has been kind to the gemstone, as its coloured varieties enjoy respectable popularity in this day and age.
General Tips on Buying and Maintaining Turquoise, Tanzanite, and Zircon
Turquoise, Tanzanite, and Zircon go by the 4 Cs for valuation.
For Turquoise, a deeply saturated, even medium blue is the most expensive, although greenish-blue gems are popular among general consumers.
Deep violet-blue Tanzanites go for the highest prices. Collectors highly prize ultra-rare Cat’s eye and deep green Tanzanites.
You can’t go wrong with bright blue Zircon, as it is the most in-demand colour. Red and green Zircon mostly get attention from collectors.
Semi-transparent or opaque Turquoise are acceptable. Turquoise with a matrix is generally cheaper, but an aesthetically pleasing spiderweb matrix can bump up the price.
The only kind of inclusion that adds value to Tanzanite is a Cat’s eye inclusion.
Most Zircon on the market has been treated to be eye-clean for inclusions. Untreated Zircon looks cloudy, and with visible inclusions, costs much less.
Safe bets for Turquoise cuts are cabochons and beads, as they show off the stone’s best properties.
You want to get Tanzanite in oval cuts, trillions, or cushions to really show off its colour.
Zircons look best cut in the brilliant style. Step and mixed cuts are also good choices.
Big, blemish-free Turquoise is rare and expensive. For typical Turquoise pieces, colour matters much more than size.
Any Tanzanite stone below 5 carats doesn’t have the deep saturation that larger stones have, so higher carat Tanzanite is generally more valuable.
Quality yellow and orange Zircons are within the 5-carat range. You’ll have to look at smaller stones if you want a purple or red stone. Blue and green gems though can be as big as 10 carats.
General Maintenance Tips
Turquoise absorbs chemicals easily and becomes darker as a result. Tanzanite is relatively soft, ranging between 6 and 7 in the Mohs hardness scale, and the same goes for Zircon. Tanzanite is better surrounded by harder metals and stones.
All three gemstones should be worn occasionally. Only clean them with mild soap, warm water, and a soft brush; never with mechanical or ultrasonic cleaning devices.