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Poised between lush blue, vibrant violet and rich purple, exotic tanzanite is found in only one place on earth, near majestic Mount Kilimanjaro.

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Unique Hues

Unique violet-to-blue hues

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Pure Blue

Tanzanite’s most-prized colour is a pure blue similar to fine sapphire.

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Tanzanite's colour blends blue hue and violet pleochroic hues.

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Tanzanian Beauty

This beautiful Merelani tanzanite crystal measures 4 x 2.9 cm.

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Pleochroic Colours

This crystal shows strong blue and brownish green pleochroic colours.

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This crystal shows traces of the rock where it grew on its base.

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Buyer's Guide

Fine tanzanite’s strong pleochroism and intense violet-to-blue face up colours help identify the gem and provide a large part of its value. Paler colours are more commonly found and less valued. Eye visible inclusions also cause a drop in value.


Use your postcode to find a jeweller near you with GIA reports and GIA-trained staff.


Verify the information on your report matches what is archived in the GIA report database.

What to look for

13.61-carat fantasy-cut tanzanite

Due to tanzanite’s strong pleochroism, each fashioned gemstone usually displays a mix of both blue and violet hues depending on viewing angle. The majority of tanzanites mined are light-to-medium purple and blue coloured stones. However, the gem is generally famed for the small number of intensely saturated, bluish-violet stones which usually occur in sizes above 5 carats.

Top quality tanzanite

Eye-visible inclusions decrease the value of tanzanite, particularly in lighter coloured stones, where they’re more visible against the gem’s body colour. Any inclusions that might pose durability problems - such as fractures - lower tanzanite value greatly.

Antique cushion-cut tanzanite

Tanzanite is available in a wide range of shapes but cushions, trillions and oval cuts are most common. The cutting orientation can emphasise which colours are seen through the gem’s crown. Cutting to display a gem’s violet colour face up usually retains more carat weight from the rough than fashioning it to display a predominantly blue hue.

Size range of tanzanite
Carat Weight

Tanzanite is available as fine, larger pieces with strong colour or lighter material cut to standard sizes for use in mass market jewellery. Tanzanite colour is less saturated in smaller sizes. Gems must be above 5 cts. in size to have deep, fine colour.

Tanzanite Quality Factors: The Comprehensive Guide

Tips & Advice

1. Size and colour are related.

Tanzanite usually has to be larger than five carats to reach a deep saturated violetish blue or bluish violet colour. Small accent stones of less than two carats in size are commonly a lighter colour.

2. Consider a protective setting.

With a hardness of 6 to 7, tanzanite is softer than many gems. Exercise a little caution with tanzanite rings. A setting that surrounds the tanzanite with metal or gems will help protect it.

3. Don’t compromise on cut.

The quality of the cut can make a big difference in beauty and brilliance. Your tanzanite should sparkle in a lively way, reflecting light back evenly across the entire gem. Poorly cut gems are much less marketable and sell at a discount.

4. Work with a knowledgeable jeweller.

Because tanzanite is an unusual gem, make sure you choose a jeweller who has gemmological knowledge and expertise. A jeweller who knows and loves tanzanite should have a selection to show you so you can see quality differences side by side.