Tanzanite: December Birthstone
ROMANCE, HISTORY & FOLKLORE
While the legends of some gemstones span millennia, Tanzanite’s story is just decades old.
In 1967, a bolt of lightning triggered a wildfire that engulfed Tanzania’s Merelani Hills, laying them bare. Passing through after the flames subsided, local Masai herders noticed brilliant blue crystals on the ground. Although the herders were unaware, they had discovered the stone’s secret: when exposed to heat, its drab brown color transforms into a thing of beauty.
The stones soon fell into the hands of a merchant named Manuel D’Souza, who mistook them for sapphires. The gemstone stumped jewelers and gemologists, until both the British Museum and Harvard University confirmed that the supposed sapphires were an entirely unknown gemstone. The newly discovered stones were named “blue zoisite.”
Tiffany & Company is credited with renaming the gemstone “Tanzanite” after its native country. Since its discovery just a half-century ago, Tanzanite has become one of the most popular gemstones in fine jewelry, and a well-known birthstone for December.
As its name suggests, Tanzanite comes from only one place in the world: the East African nation of Tanzania.
Mined from the Merelani Hills at the base of Mount Kilimanjaro, the Tanzanite deposits lie within a slender strip of ground just five miles wide.
SELECTING A STONE
With its array of indigo hues and variety of shapes, Tanzanite is a mesmerizing gemstone. Each gemstone is unique, conveying auras from dignified to delicate; it is a gem that suits any personality.
In its untreated form, Tanzanite is a trichroic gem, meaning it shows three colors when viewed at different angles. One direction is blue, another purple, and the other brown.
All Tanzanite demonstrates a striking response to lighting. Daylight brings out its true-blue hues, while incandescent light emphasizes its indigo tones. Generally speaking, the deeper blue a Tanzanite gemstone is, the more value it carries.
Because of its trichroism and cleavage, Tanzanite requires an experienced lapidary who is able to maximize both the stone’s size and unique color. Fortunately, Tanzanite is a plentiful stone, allowing cutters room for creativity. While cushions cuts are commonly used for larger pieces of Tanzanite, combination cuts, fantasy cuts, trilliants, and round cuts are also popular.
Though Tanzanite is available in large sizes suitable for major rings and pendants, it is frequently set into necklaces or earrings more suitable to its soft nature.
With the exception of the few stones that yielded Tanzanite’s discovery, it is universally heat-treated to produce purplish-blue hues. In its unheated form, Tanzanite appears dull gray and brown.
Because heat treatment of Tanzanite is universal, it has no effect on stone’s price, unlike most other gemstones. Heat treatment is a permanent enhancement which will remain unaffected by cutting and polishing.
Like Pearl or Opal, Tanzanite is a gemstone that requires special care.
With a hardness of 6.5, Tanzanite can be scratched if brought into contact with other gemstones. Take care to store Tanzanite jewelry in its own protective pouch to avoid scratching or chipping.
At-home cleaning is recommended every second or third wear. Let a piece soak for a few minutes in a gentle detergent solution and use a soft brush to clean around the setting. Pat dry with a soft, absorbent cloth, or allow to air-dry.
For professional cleaning, never put a Tanzanite in an ultrasonic machine, and never subject it to steam.