December Birthstone
Tanzanite
Also: Zircon · Turquoise
"Transformation, wisdom, and higher consciousness"
About Tanzanite
Chemical Formula
Ca₂Al₃(SiO₄)₃(OH) (zoisite)
Crystal System
Orthorhombic
Hardness
6–7 on Mohs scale
Color
Blue-Violet
Primary Origins
Tanzania (only source for tanzanite), Global (turquoise, zircon)
December has three birthstones — tanzanite, zircon, and turquoise — and the range they represent is remarkable: the newest named gemstone in history, one of the oldest minerals on earth, and a blue-green gem traded across continents for seven thousand years. Tanzanite was unknown to the world until 1967. Manuel d'Souza stumbled on the glittering blue crystals in the Merelani Hills of Tanzania while prospecting for rubies, and within a year Tiffany & Co. had named it, packaged it, and launched what became the most successful gemstone introduction of the 20th century. The specific quality that makes tanzanite extraordinary is its trichroism: the stone shows different colors — blue, violet, and burgundy — depending on which angle you view it from and what kind of light you see it under. Cut and heat-treated to emphasize the blue-violet range, fine tanzanite has a depth of color that shifts as you move it, never quite settling on a single definition. It is also, crucially, found in only one place on Earth: a four-kilometer stretch of metamorphic rock near Kilimanjaro. When those deposits are exhausted, tanzanite will be gone. This is either a concerning footnote or a compelling reason to own one, depending on your disposition. Turquoise — the oldest of December's three — has been mined in the Sinai Peninsula since at least 5000 BCE, traded to Egypt and beyond, carved into protective amulets in ancient Egypt and Persia, and woven into the cultural traditions of the American Southwest's Native peoples for centuries. Something this old and this widespread has earned whatever meaning it carries. December birthdays have choices that span the full history of human gem use: from the seven-thousand-year-old turquoise to the fifty-year-old tanzanite.
History
Tanzanite was discovered in 1967 in the Merelani Hills of Tanzania by a Maasai tribesman, Ali Juuyawatu, and brought to international attention by tailor Manuel d'Souza, who reported the find to the Tanzanian government. Tiffany & Co. recognized the stone's commercial potential and named it "tanzanite" (after Tanzania) in 1968, launching it as the first major new gemstone to enter the market in over 2,000 years [American Gem Society, ags.org; GIA, gia.edu]. Tanzanite was added as an official December birthstone in 2002 by the American Gem Trade Association. The stone occurs in only one location on Earth — a four-kilometer stretch near Kilimanjaro — making it genuinely one-of-a-kind.
Mythology & Cultural Traditions
Because tanzanite was discovered only in 1967, it lacks the ancient mythology of older gemstones. The Maasai people of Tanzania, however, have adopted it into their cultural tradition: Maasai women are presented with tanzanite beads after giving birth as a symbol of a healthy new life and good fortune for the child. The color — shifting between blue and violet depending on the angle and light source — is seen as representing the two complementary qualities of wisdom (blue) and spirituality (violet). December's two other birthstones — turquoise, one of the world's oldest gems, mined for 7,000 years, and zircon, often mistaken for diamond — offer their own mythological depth.
Geology & Formation
Tanzanite is the blue-violet variety of zoisite, a calcium aluminum silicate mineral. Its extraordinary trichroism — displaying different colors (blue, violet, and burgundy) depending on the viewing angle — comes from vanadium and chromium impurities. Most tanzanite is heat-treated to reduce the burgundy component and intensify the blue-violet. The geological conditions that created tanzanite required the simultaneous occurrence of several rare geological events, which is why it occurs in only one place on Earth. Zircon (an alternate birthstone) is one of Earth's oldest minerals, with crystals dated to 4.4 billion years ago. [Source: GIA Gem Encyclopedia, gia.edu; Mindat.org]
Famous Tanzanites
The Queen of Kilimanjaro
A 242-carat tanzanite set in a tiara surrounded by 803 tsavorite garnets and 913 diamonds, created by Michael Scott in 2005 — one of the most notable tanzanite gems in existence.
Natural Turquoise: Sleeping Beauty Mine
The Sleeping Beauty Mine in Globe, Arizona, closed in 2012, produced the most uniform robin's-egg blue natural turquoise in the world — now extremely sought-after and valued by collectors.
Did You Know?
Tanzanite is found in only one location on Earth: a four-kilometer stretch near Mount Kilimanjaro in Tanzania. Once exhausted, it cannot be replaced.
Tiffany & Co. is credited with naming tanzanite and launching it commercially in 1968 — effectively introducing the first major new gemstone to the market in over 2,000 years.
Turquoise, one of December's alternates, was the first gem ever to be traded across continental distances — turquoise from the Sinai Peninsula was traded to Egypt over 7,000 years ago.
Care Instructions
Tanzanite is relatively soft (Mohs 6–7) and should be protected from hard blows and scratches. Avoid ultrasonic cleaners and steam — warm soapy water and a soft cloth only. Tanzanite is also sensitive to thermal shock (sudden temperature changes). Turquoise is porous — avoid chemicals, perfume, and prolonged water exposure. [GIA, gia.edu]
Frequently Asked Questions
What is the birthstone for December?
The primary birthstone for December is Tanzanite, with alternates including Zircon and Turquoise.
What color is Tanzanite?
Tanzanite is Blue-Violet. Its chemical formula is Ca₂Al₃(SiO₄)₃(OH) (zoisite).
What does Tanzanite symbolize?
Tanzanite symbolizes Transformation, wisdom, and higher consciousness.
How hard is Tanzanite?
Tanzanite rates 6–7 on Mohs scale on the Mohs scale.
Where is Tanzanite found?
Tanzanite is primarily found in Tanzania (only source for tanzanite), Global (turquoise, zircon).
How should I care for Tanzanite jewelry?
Tanzanite is relatively soft (Mohs 6–7) and should be protected from hard blows and scratches. Avoid ultrasonic cleaners and steam — warm soapy water and a soft cloth only. Tanzanite is also sensitive to thermal shock (sudden temperature changes). Turquoise is porous — avoid chemicals, perfume, and prolonged water exposure. [GIA, gia.edu]
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