Tanzanite: A Buyer's Guide
Tanzanite comes from one hillside on earth, and that hillside will run out. It is also softer than almost anyone selling it will tell you — both facts matter before you buy.
What tanzanite actually is
Tanzanite is the blue-violet variety of zoisite, coloured by trace vanadium. It was found in 1967 in the Merelani Hills of northern Tanzania, and Tiffany & Co. named it the following year — the mineral name, blue zoisite, was judged unsellable.
The deposit covers roughly eight square kilometres. That is the entire world supply, and it is the only known occurrence of gem-quality blue zoisite anywhere. Estimates of remaining life vary considerably, but nobody disputes the direction: this is a finite stone with a visible end.
Trichroism — the property that shapes everything
Tanzanite is strongly trichroic. It shows three different colours along three different crystal axes: blue, violet-purple, and a burgundy or brownish red.
This is why cutting matters more here than in most stones. A cutter can orient for maximum blue or for maximum weight, rarely both. Orienting for blue means sacrificing yield, so weight-oriented stones look more violet or brownish face-up and cost less for good reason.
It also means tanzanite genuinely changes character under different lighting. Daylight brings out the blue; incandescent light pushes it violet. This is not colour change in the alexandrite sense — it is the same three colours reading in different proportions. Look at any tanzanite in both before deciding.
Heat treatment
Almost all tanzanite in the ground is brown or khaki. Heating to around 500–600°C removes the brown and produces the blue-violet the market wants.
This treatment is universal, permanent, stable and entirely accepted. It does not reduce a stone's standing and no serious buyer avoids it. Untreated blue tanzanite exists but is genuinely rare, and material that occurs naturally blue is not meaningfully different from heated once both are cut.
If a dealer presents unheated tanzanite as significantly superior, be sceptical. The treatment is so universal and so accepted that the distinction carries far less weight than it does in sapphire or ruby. It is more often a selling point invented for buyers who have read about unheated sapphire and assume the same logic applies.
What to screen for instead: coated and diffused material, where colour is applied to the surface. It exists, and it is detectable by laboratory examination.
What determines quality
Colour
The dominant factor. The market rewards deep, saturated violetish blue — the deeper and more vivid, the better. Pale, greyish and overly violet stones sit well below. The finest material is sometimes graded as AAA or block D by dealers, though these are trade conventions rather than a laboratory standard.
Size
Colour saturation depends heavily on size. Small tanzanites look pale because there is not enough material for the colour to develop; the same rough cut larger reads dramatically deeper. Below 1ct, tanzanite rarely shows what makes it worth owning. Above 5ct, deep saturated stones become genuinely sought.
Clarity
Tanzanite forms relatively cleanly and eye-clean is the expectation. Visible inclusions matter, and fractures matter more than usual because of the cleavage.
Cut
Judge face-up, always. A well-oriented 3ct stone reads far better than a weight-oriented 4ct one. Windowing is common in stones cut to preserve carat weight.
Durability — the part that gets undersold
Tanzanite is Mohs 6–6.5 with one direction of perfect cleavage. In practical terms: it scratches from ordinary household dust, which contains quartz at Mohs 7, and it can split cleanly along the cleavage plane from a knock that a sapphire would shrug off.
| Use | Suitability |
|---|---|
| Pendants, earrings | Excellent. The stone is protected and rarely struck |
| Occasional-wear rings | Good with a protective setting |
| Daily-wear engagement ring | Not recommended |
| Ultrasonic or steam cleaning | Never |
We will say this plainly to anyone who asks for a tanzanite engagement ring: the stone will not survive decades of daily wear looking as it does now. If you want that colour in a ring worn every day, a fine blue-violet sapphire is the honest answer. If you want tanzanite specifically, a pendant is where it belongs.
Setting tanzanite
Platinum and white gold emphasise the violet and give the cleanest read. Yellow gold warms it and can push the stone toward grey. Rose gold generally fights it.
For rings, bezel or half-bezel settings protect the girdle where cleavage damage starts. Avoid high-set solitaires with exposed edges. For pendants and earrings, nothing is off the table.
Care: warm soapy water and a soft cloth. No ultrasonic, no steam, no sudden temperature change. Remove it before anything physical.
How we source tanzanite
Sourced to order through our Tanzanian and Jaipur supply lines. Tell us the carat range and how deep you want the colour; those two interact, since saturation builds with size.
Every candidate is filmed in daylight and under warm indoor light, because the trichroism means the stone genuinely presents differently in each and you should see both before deciding. Stones come with a laboratory report confirming natural zoisite and treatment status.
Turnaround is typically 3 to 7 days for commercial material, two to four weeks for deep-saturation stones above 5ct.
Frequently asked questions
Is tanzanite really running out?
The entire world supply comes from roughly eight square kilometres in the Merelani Hills of Tanzania, and it is the only known gem-quality blue zoisite deposit anywhere. Estimates of remaining life vary widely and anyone quoting a precise year is guessing. What is not in dispute is that supply is finite and there is no second source to find.
Can tanzanite be worn as an engagement ring?
We do not recommend it. At Mohs 6–6.5 with one direction of perfect cleavage, tanzanite scratches from ordinary household dust and can split from a knock a sapphire would ignore. It will not survive decades of daily wear looking as it does now. For that colour in a daily ring, a blue-violet sapphire is the honest answer.
Is heated tanzanite less valuable than unheated?
Not meaningfully. Almost all tanzanite in the ground is brown, and heating to around 500–600°C is universal, permanent, stable and entirely accepted across the trade. If a dealer presents unheated tanzanite as significantly superior, be sceptical — the distinction carries far less weight here than it does in sapphire or ruby.
Why does my tanzanite look different indoors?
Trichroism. Tanzanite shows three colours along three crystal axes — blue, violet-purple and a burgundy red. Daylight brings out the blue; incandescent light pushes it violet. This is normal and is part of the stone's character, not a fault. Always look at a tanzanite in both lights before buying.
What size tanzanite should I buy?
Larger than you might for other stones. Colour saturation in tanzanite depends heavily on size — small stones look pale because there is not enough material for the colour to develop. Below 1ct tanzanite rarely shows what makes it worth owning. If budget forces a choice, go larger rather than deeper.
How should I clean tanzanite?
Warm soapy water and a soft cloth only. Never ultrasonic, never steam, and avoid sudden temperature changes — the cleavage makes it vulnerable to thermal shock. Store it separately from harder stones, since almost everything in a jewellery box will scratch it.
What is AAA tanzanite?
A trade grading convention rather than a laboratory standard. Dealers use AAA, AA and A, or a block system running from D upward, to describe colour saturation. There is no governing body behind these labels and they are applied inconsistently between sellers. Judge the stone, not the grade letter.
Do you ship tanzanite internationally?
Yes, worldwide, with insured tracked courier and full customs documentation. Because tanzanite presents so differently under different lighting, we film every candidate in both daylight and warm indoor light before you commit, and we will do a live call if you want to see it moving.
Enquire About a Tanzanite
Tell us the carat range and how deep you want the colour. We will source certified options and film each stone in daylight and indoor light so you see how it actually behaves.
Tinch Jewels · Borivali West, Mumbai 400092, India · Worldwide insured shipping
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