December’s birthstones offer two ways to fight the winter blues: tanzanite, and turquoise – both of them, appropriately, best known for beautiful shades of blue.
These gems range from the first mined and used in jewelry (turquoise), to one of the most recently discovered (tanzanite).
Both of these stones are relatively inexpensive, but their beauty rivals even precious gems. Tanzanite often substitutes sapphire, and turquoise is unmatched in its hue of robin’s egg blue.
Whatever your style preference or budget, one of December’s birthstones will match your true blue desires.
Tanzanite is the exquisite blue variety of the mineral zoisite that is only found in one part of the world. Named for its limited geographic origin in Tanzania, tanzanite has quickly risen to popularity since its relatively recent discovery.
Zoisite had been around more than a century and a half before this rare blue variety was found in 1967. Trace amounts of vanadium, mixed with extreme heat, cause the blue color – which ranges from pale blue to intense ultramarine with violet undertones.
Due to pleochroism, tanzanite can display different colors when viewed from different angles. Stones must be cut properly to highlight the more attractive blue and violet hues, and deemphasize the undesirable brown tones.
The majority of tanzanite on the market today is heat treated to minimize the brown colors found naturally, and to enhance the blue shades that can rival sapphire.
Tanzanite is still only found on a few square miles of land in Tanzania, near majestic Mount Kilimanjaro. Its price and availability are directly tied to mines in this region.
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.
Between its deep blue color and its limited supply, tanzanite is treasured by many – whether one is born in December or not!
Unlike many well-known gems that have been in use for centuries, tanzanite’s history is relatively modern.
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. They notified a prospector named Manuel d’Souza, who promptly registered claims with the government to begin mining.
Initially, d’Souza thought he was mining sapphire, but the crystal was soon identified as a vibrant blue variety of zoisite – a mineral that had been around since the early 1800s.
Tiffany & Co. recognized this blue gem’s potential to rival more expensive sapphire, and agreed to become its main distributor. Instead of publicizing “blue zoisite” – which sounded a little too much like “suicide” – Tiffany named the gem tanzanite to highlight its exclusive geographic origin, and introduced it with a promotional campaign in 1968.
An estimated two million carats of tanzanite were mined before the Tanzanian government nationalized the mines in 1971. The government divided the mines into four sections, or blocks, in 1990. TanzaniteOne Mining Ltd., the world’s largest tanzanite producer, holds the rights to Block C, which is larger than the other blocks combined.
An independent study from 2012 suggests, at a production rate of 2.7 million carats per year, that Block C’s tanzanite deposits may deplete in as soon as 30 years.
Tanzanite may not have the long history of other gems, but with such limited supplies and rapidly growing popularity, it is highly prized for its rare beauty.