Fine Coloured Stones
Tanzanites
Blue · Violet-Blue · Violet · Purple
Varieties
How tanzanites are categorised
Trade categories rather than gemological ones — these are the terms a requirement is normally written in.
- Blue-dominant Tanzanite
- The premium end; blue reads first, violet second.
- Violet-dominant Tanzanite
- The broader commercial supply.
- Calibrated & Parcels
- Small sizes for volume production.
Tanzanites in detail
Colour, size and pleochroism
Tanzanite is strongly pleochroic — it shows blue, violet and a brownish or burgundy direction depending on how you look at the crystal. The cutter chooses which of those faces up, and that decision drives the price more than anything else.
Blue-dominant stones sit above violet-dominant ones commercially. Depth of colour also increases with size: small tanzanite is almost always lighter and more violet, and the strong blues appear as the stones get larger.
If you are specifying tanzanite for a collection, specify the blue-to-violet balance and the tone, not just "tanzanite".
Setting and durability
Tanzanite is softer than corundum and has a cleavage direction. It is well suited to earrings, pendants and occasional-wear rings, and it needs care in everyday ring wear and at the bench.
Avoid ultrasonic cleaning and sudden temperature change. Protective settings are worth considering for anything that will be worn daily.
Treatment
Effectively all tanzanite on the market is heated — the treatment produces the blue-violet colour from material that is typically brownish in its natural state. It is standard, stable and expected throughout the trade. Unheated tanzanite is not a normal commercial category.
This describes the market for the species. It is not a statement about any individual stone — disclosure for a specific stone comes from that stone’s own record and documentation. More on laboratory reports.
Buyer questions
Buying tanzanites
- Is heated tanzanite normal?
- It is effectively universal. The heating produces the colour the stone is bought for, it is stable and permanent, and it is expected throughout the trade rather than being a defect.
- Can you supply calibrated tanzanite?
- Yes, in the smaller commercial sizes. Bear in mind that small tanzanite is naturally lighter and more violet — if you need strong blue, that has size implications.
- Is tanzanite suitable for an everyday ring?
- With a protective setting and realistic care advice to the customer, yes. For daily wear without those, sapphire or spinel is the sounder recommendation and we will say so.