Tanzanite Guide

Pictured above: Fergus James 3ct Oval Tanzanite Trilogy Ring White Gold

Tanzanite is the blue-to-violet variety of zoisite.

It was discovered in northern Tanzania in 1967 and named after the country where it was found. Unlike many other important gemstones, tanzanite has only one known commercial source: the Merelani Hills near Mount Kilimanjaro.

That extremely limited geographic source is one of the characteristics that makes tanzanite so unusual.

Tanzanite is also one of the modern December birthstones, alongside turquoise and zircon, and is associated with the 24th wedding anniversary.

Pictured above: Fergus James 13 Carat Natural Tanzanite Tennis Bracelet

Tanzanite doesn't have a universally standardised quality-grading system equivalent to diamonds.

Colour, clarity, cut and carat weight all matter - but for us:

Colour comes first.

One of tanzanite's most distinctive characteristics is pleochroism.

This means the gemstone can display different colours when viewed from different crystal directions. In tanzanite, those colours can include blue and violet, as well as yellow-green or brownish tones in untreated material.

Lighting also affects how the stone appears.

Cooler daylight-style lighting → can emphasise blue

Warmer lighting → can bring out more violet or purple

As a result, the same tanzanite can appear noticeably different throughout the day.

Most tanzanite available in the jewellery market has been heat treated.

Untreated tanzanite rough can contain yellow-green or brownish colour components. Heating typically reduces those tones and strengthens the blue and violet colours associated with fine tanzanite.

Heat treatment is widely accepted within the trade and isn't automatically a negative.

What matters is disclosure.

You should understand whether a stone has been treated and what effect that treatment has had on its appearance.

Naturally blue, unheated tanzanite exists but is considerably less common.

Tanzanite has an unusually simple origin story:

It comes from one place.

Commercially mined tanzanite is found only in the Merelani Hills in northern Tanzania, near Mount Kilimanjaro.

That makes its geographic origin fundamentally different from sapphire, ruby or emerald, which are mined in multiple countries.

Not every tanzanite will be accompanied by an independent gemological report, particularly smaller stones used within jewellery.

For significant stones, however, a laboratory report can help establish information such as:

Whether the gemstone is natural

Its weight and measurements

Whether detectable treatment is present where relevant

Basic gemological identification

Because tanzanite has only one commercial source, geographic-origin reporting is generally less of a buying issue than it is for emerald, ruby or sapphire.

One of the most appealing things about tanzanite is that it rarely looks exactly the same twice.

Depending on the lighting, viewing angle and cut orientation, a stone can shift between blue, violet and deeper purple tones. That changing appearance is a genuine part of tanzanite's character rather than a flaw.

Some clients initially compare it with blue sapphire, but the two have very different personalities. Tanzanite tends to show a more fluid blue-violet character, while sapphire often presents a more stable blue.

Our specialists can help you visually compare individual stones, focusing on differences in colour, saturation, brightness and overall appearance to find the tanzanite that best suits your preference.

The individual gemstone matters more than its description or specifications alone.

It can be, but it requires more care than sapphire, ruby or diamond.

Tanzanite ranks around 6–7 on the Mohs scale, meaning it's more vulnerable to scratching than many gemstones commonly chosen for everyday rings.

Hardness also isn't the only consideration. Tanzanite can be vulnerable to impact and sudden temperature changes, so we'd be more cautious with it in jewellery that's exposed to frequent knocks.

Tanzanite can look beautiful across many types of fine jewellery:

Rings · Earrings · Pendants · Bracelets

Because of its durability, we'd generally be most relaxed using tanzanite in earrings and pendants, where the stone is naturally less exposed to impact.

For rings, protective designs and sensible wear become more important.

Tanzanite also pairs particularly well with colourless diamonds, which can create contrast and emphasise its blue-violet colour.

Pictured above: Fergus James 12ct Natural Tanzanite Tennis Bracelet Yellow Gold

There's no universally best choice.

Tanzanite and blue sapphire can both provide beautiful blue colour, but they're very different gemstones.

Tanzanite is often associated with transformation, new beginnings and individuality, which fits naturally with its relatively recent discovery and distinctive appearance.

It is also a December birthstone and is associated with the 24th wedding anniversary.

These associations can make it meaningful for milestone jewellery, although we'd always recommend choosing tanzanite primarily because you love the gemstone itself.

Tanzanite requires more careful handling than harder gemstones.

We'd recommend:

Removing it before exercise, sport or manual work

Protecting it from knocks and impacts

Avoiding harsh chemicals and sudden temperature changes

Storing it separately from harder gemstones such as diamonds and sapphires

Clean tanzanite gently using warm water, mild soap and a soft brush.

Because of its relative softness and sensitivity, we'd avoid ultrasonic or steam cleaning unless a professional jeweller has confirmed it's appropriate for the specific piece.

Frequently worn tanzanite rings should also be periodically inspected for setting security.