Tanzanite: Meaning, Symbolic Properties and Care

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Tanzanite is the blue-violet variety of zoisite, discovered in Tanzania in the 1960s. A recent gem, fragile and almost always heat-treated.

Key points

Colours	sapphire blue, violet, blue-violet; brownish or greenish tints before heating
Mineral family	calcium aluminium silicate (zoisite), orthorhombic system
Mohs hardness	6 to 6.5
Discovery	1967, Merelani Hills (Tanzania)
Deposit	a single commercial mining area: Merelani
Treatment	heating, applied to the great majority of stones
Birthstone	December (according to modern lists)

What is tanzanite?

Tanzanite is a blue to violet variety of zoisite, a calcium aluminium silicate with traces of vanadium. Its hardness is 6 to 6.5. It was discovered in 1967 in the Merelani Hills of Tanzania, at the foot of Kilimanjaro; its name recalls that country. According to the Gemological Institute of America (GIA), the Merelani area remains the only known commercial mining zone.

The jewellery house Tiffany did a great deal to make the stone known to the public in the late 1960s. Today, tanzanite appears in several modern lists of December birthstones (see December birthstones).

A stone with several colours

Tanzanite is pleochroic: the same crystal shows different colours depending on the direction from which it is viewed (deep blue, violet, sometimes a yellow-green or brown). Cutters therefore orient the stone to bring out the blue and violet. Rough crystals often have brownish or greenish tints, which heating (to about 500 degrees) turns into blue-violet: this is a very common treatment, accepted in the trade, provided the buyer is aware of it.

Traditional symbolism

Tanzanite is too recent to have an ancient tradition. Contemporary writers associate it with transformation, intuition and sensitivity, drawing on its colours, which change with the angle. Some call it the “stone of change”.

These are modern interpretations, not facts. A tanzanite should be chosen first for its beauty.

Traditional correspondences

Element	Association cited
Chakra	third eye and crown, sometimes throat
Element	water or air
Signs	divergent; Sagittarius, Libra or Pisces depending on the author
Keywords	intuition, change, serenity

You may also read the page on the third eye.

How to use it

As evening jewellery: a ring or pendant worn for occasions rather than every day.
As earrings, which are less exposed to knocks.
As rough crystal (when sold as such) to observe in the light.
As a December gift for a birthday.

Whatever the use, keep in mind that tanzanite must be handled with care: store it in a separate pouch, away from harder stones, and avoid wearing it for manual tasks. No stone has a proven effect on health or destiny; it is above all an object of beauty and a personal symbol.

Care and cleansing

Tanzanite is more fragile than it looks: hardness 6 to 6.5 and cleavage (it can split on a knock). Clean it with lukewarm soapy water and a soft brush, then dry. Avoid ultrasonic cleaners, steam, sudden temperature changes, strong heat (which can alter the colour) and contact with chemicals. Take it off for housework, gardening and sport.

For symbolic cleansing: gentle smoke or moonlight. More ideas in cleansing and recharging your stones.

Treatments and imitations

Heating: the great majority of tanzanites are heated. This is not a defect, but it should be disclosed.
Imitations: blue-violet glass, synthetic sapphire, laboratory spinel or corundum, iolite or other blue-violet stones. Some, such as iolite, are natural but of a different species.
Doublets (two pieces glued together): look for bubbles or a glue line under a loupe.
A very low price for a “large tanzanite” is a warning sign. For a valuable stone, ask for a laboratory certificate.

How to choose it

Look at the colour in natural light and under a lamp: it can change. Intense blue-violet stones that are transparent and free of cracks are the most sought after and can be expensive; small cabochons or rough crystals are much more affordable. For an everyday piece, a harder stone such as sapphire or iolite is more durable. Tanzanite is a variety of zoisite. For the basics, see choosing and caring for your stones.