Tanzanite
Tanzanite — Between Blue and Violet
Tanzanite is known for its blend of blue and violet, from pale shades to deep, saturated colour. It is the blue-violet variety of zoisite, commercially sourced from the Merelani Hills of northern Tanzania.
The Name
Tiffany & Co. named the gemstone after Tanzania. Its discovery in the Merelani area in 1967 brought it to the attention of the jewellery world. Although it belongs to zoisite, its colours and character deserve a closer look of their own.
Gemmological Properties
| Mineral / material | Zoisite, the blue-violet variety |
|---|---|
| Composition | A calcium aluminium silicate containing hydroxyl; vanadium is an important colour-producing element |
| Colours | Violet blue, bluish violet and violet |
| Hardness | 6–7 on the Mohs scale |
| Refractive index | 1.691–1.700 |
| Specific gravity | Approximately 3.35 |
| Optical phenomena | Strong pleochroism and double refraction; a rare cat’s-eye effect |
| Toughness | Has cleavage; its hardness does not indicate high resistance to impact |
These are general reference values, not test results for an individual stone.
Colour and Optics
Tanzanite can display different colours when viewed along different crystal directions, a property called pleochroism. Cutting orientation influences the balance of blue and violet seen face-up. Lighting also affects its appearance: cooler light can emphasise blue, while warmer light can bring out violet. This does not necessarily represent a separate colour-change phenomenon.
Quality and Price
Colour, clarity, cutting and carat weight influence price. Attractive saturation, good light return and an eye-clean appearance contribute to value; fractures and obvious inclusions can reduce it. Paler shades can also suit a beautiful, subtle design. Labels such as AAA are not standardised grades across the market, so the individual stone matters more than the label.
Treatments and Identification
Most blue tanzanite on the market has been heated to reduce brownish or yellow-green shades and emphasise blue and violet. The treatment is considered stable under normal wearing conditions. Heating does not make a natural stone synthetic, and testing cannot always establish whether an individual stone has been heated.
Colour coatings and fracture filling have also been documented, but are less common and differ from heating. Colour alone cannot establish identity: optical properties, inclusions and treatment evidence are examined. Known treatments should be disclosed.
Suitability for Setting
Tanzanite is particularly suited to earrings and pendants. It can also be used in rings, but its cleavage and limited toughness call for a protective design suited to the stone’s condition and intended use. A surrounding setting can protect its edges. For a ring exposed to frequent impacts, a tougher gemstone may be preferable.
Sources Around the World
The familiar commercial source of tanzanite is the Merelani Hills of northern Tanzania, near Arusha. This source refers to the blue-violet variety of zoisite rather than all appearances of the mineral.
Spiritual and Symbolic Meaning — Beliefs and Traditions
In spiritual traditions, tanzanite is associated with connecting thought and feeling, listening to the heart while maintaining clear awareness. It symbolises openness to new insights, a sense of wholeness and honest expression of one’s inner world. Chakra traditions associate it with the heart, third eye and throat, representing a connection between understanding, listening and expressing feelings. In personal jewellery, it can serve as a reminder to acknowledge the heart’s wishes and express them with honesty and sensitivity.
These meanings belong to the realm of belief and symbolism. They can give jewellery personal significance, but they are not proven gemological properties or a promise of healing, protection or a change in health.
Your Tanzanite, in Jewellery Created for You
At TzurGems, we combine Guy’s gemological knowledge with the craftsmanship of Rafael, an artisan goldsmith. We examine the stone’s colour, cut and condition, then design jewellery that highlights its character and suits the person who will wear it.