December Birthstone – Tanzinite
December has not one but THREE birthstones . Celebrating Summer with various hues of the ocean, we get Tanzanite, Zircon and Turquoise – all of them, appropriately, best known for their beautiful shades of blue.
These gems range from the oldest on earth (Zircon), to one of the first mined and used in jewellery (Turquoise), to one of the most recently discovered (Tanzanite).
Whatever your style preference or budget, one of December’s three birthstones will match your true blue desires. Today we’re going to take a closer look at Tanzanite.x
Found on a few square miles of land near majestic Mount Kilimanjaro, it’s price and availability are directly tied to mines in this region.
The common story of tanzanite’s discovery tells of Maasai herders who found blue crystals in the Merelani Hills near Arusha, Tanzania, while tending livestock in 1967.
Initially thought to be sapphire, tanzanite was soon identified as a vibrant blue variety of zoisite – a mineral that had been around since the early 1800s. Trace amounts of vanadium, mixed with extreme heat, cause the blue colour – which ranges from pale blue to intense ultramarine with violet undertones.
Tanzanite measures 6.5 to 7 on the Mohs scale of hardness – which is not nearly as hard as the sapphire it often substitutes. Given its vulnerability to scratch during daily wear and abrasion,Tanzanite is better suited for earrings and pendants than rings.
How to Buy Tanzanite
Most tanzanite on the market today gets its blue colour from heat treatment, which minimises the stone’s natural brown hues. Treated tanzanite has become the norm, so although it’s undetectable, it’s usually assumed.
Colour – This is tanzanite’s most prized trait, especially when it’s deeply saturated blue with violet hues. Paler shades are less expensive. The stone is pleochroic, which means it displays different colours from different angles.
Cut – The cut significantly influences the colour, which determines the price. Cutting a stone to emphasise the blue may waste more of the rough, but because this colour is more valuable than violet, the cutter may choose a small coloured blue gem over a larger violet one.
Clarity – Tanzanite is usually free of eye-visible inclusions. If any inclusions are present (especially those that pose a durability problem, such as fractures) they typically lower the value.
Carat – Fine tanzanite with a strong, deep colour can be found in pieces weighing 5.00 carats or more. Smaller sizes in less saturated colours are commonly seen in mass market jewellery.