GIA GEMOLOGIST ARTICLE

The Definitive Tanzanite Buying Guide

Everything you need to know about Tanzanite. Learn all about this beautiful, rare gemstone. Learn about its properties, how to judge quality, pricing, how it is mined, where it comes from and how to spot imitations.

Antony Zagoritis

GIA Graduate Gemologist
ICA Ambassador to Kenya

Tanzanite is a complex gemstone and researching its properties can be confusing, particularly online as there is so much conflicting information depending on where you look. This guide aims to create a definitive reference for those looking to understand Tanzanite quality and properties in order to purchase in a more informed manner. We crosslink to our series of gemologist written articles on Tanzanite to deepen your understanding further on each subject.




WHAT IS TANZANITE?


Tanzanite is actually a Blue Zoisite and part of the Epidote group of minerals.


It was given its name by Tiffany's who had exclusive marketing rights to it for the first few years after its discovery. Its name is a reflection of the only known source in Tanzania. In the past half decade it has become the most popular colored stone in the market after Blue Sapphire. Quite an achievement for such a young gemstone. 

All of the known deposits of Tanzanite are confined to a small area in northern Tanzania in a location called Merelani near the gem trading town of Arusha. 

Merelani Tanzanite town.jpg
Entering the mining hamlet of Merelani on a dusty road from Arusha


It is the only gem type with an established and ever-increasing demand that has such a limited known supply. It is widely acknowledged that the current Tanzanite resource could be depleted in just a few decades and as such it has become known as a "One Generation Gemstone".


Next let's take a look at what you need to know in order to understand quality in Tanzanite.





HOW TO JUDGE QUALITY IN TANZANITE


Tanzanite, as with Diamonds, and all gemstones alludes to the 4 C’s of quality - COLOR, CLARITY, CARAT WEIGHT AND CUT. These are where you look to judge quality in a Tanzanite.



TANZANITE COLOR

This is the most important factor by far but also perhaps the hardest of the 4 C’s to judge online, due to many factors, not least the unreliability of images shown on different seller’s websites. Basically speaking, color saturation defines color quality. Think of color saturation as intensity - how vivid and intense is the color? The picture below demonstrates how as the depth of color declines in a Tanzanite, so does the rarity and quality.


Tanzanite Color Intensities.jpg


The first of our gemologist written articles in the series How Color Affects Value in Tanzanite goes into depth on this subject and should be your first step in learning about color.

The next obstacle to overcome is to learn about the different color grading systems there are out there. You will encounter many as you research, from the GIA system to the Tanzanite Foundation system and the IGSL system. All have their own approaches. 

The second article in our gemologist written series addresses this and will leave you with a better understanding - Tanzanite Color Grading Systems - So Many Out There Which to Trust? The article looks at the main systems in use today including the Tanzanite Foundation system, the GIA system and others.

A good understanding of how these systems work will help you enormously when browsing stones online (or in a store for that matter).


TANZANITE CLARITY

Tanzanite can be flawless or it can be heavily included. Its quality and value is profoundly affected by its clarity grade. Hence, it is very important to understand the different terms in use in the industry and which inclusions you may find in Tanzanite.


Tanzanite Inclusions Healed Fracture.jpg

"Fingerprint" liquid inclusion in Tanzanite

The image above shows a common inclusions found in the gem type - a "fingerprint" liquid inclusion. The third article in our article series Tanzanite Clarity Grading - How to Judge Clarity in Tanzanite is an excellent resource and will leave you better informed about Tanzanite inclusions, clarity grades in different grading systems and generally how clarity affects the Tanzanite’s grade.

Generally speaking, Tanzanite needs to be flawless to be considered top grade as it is classed as a Type 1 gemstone by the GIA. 


TANZANITE CUT

Whereas the actual shape of a Tanzanite has little impact on its value, the quality of the cut itself is very important. It is an area which is often overlooked in this age of catalog websites which sell huge quantities of medium grades cut in the cutting houses of India. These cutting houses generally use a myriad of weight saving techniques when cutting which can increase the finished weight of a Tanzanite by up to 30%. This means the actual hidden cost of a Tanzanite can be vastly greater than you realize.


Tanzanite bulged.jpg


The image above for example demonstrates how with a bulged pavilion, you can end up buying a Tanzanite that carries much more weight in the pavilion (back) than a properly cut stone, hence pushing up your actual cost.

Conversely a Tanzanite that is cut too shallow will display an ugly "window" effect which will severely affect its beauty and value.

The third article in our series Tanzanite Cut - Often Overlooked but Very Important is vital reading in gaining an understanding of this aspect of Tanzanite quality.


TANZANITE CARAT WEIGHT

This is the last of the 4 C’s and the one with the least impact on quality. A carat is a unit of weight measurement and is in fact 1/5 of a gram  (as opposed to "karat" which is a ratio used to indicate gold purity).


1ct to 10 ct Tanzanite size.jpg

A 10 carat Tanzanite next to a 1 carat on a gem tray

Generally speaking, the larger the Tanzanite crystal in the same quality bracket the rarer it is. This is because larger crystals have taken longer to grow and considering that Tanzanite can take over 500 million years to form, this is saying something!

Carat weight becomes important within quality brackets. A 3 carat exceptional, investment grade color with top clarity will of course always be much rarer and more valuable than a 10 carat B grade color containing inclusions.

Carat Weight versus Face Up Dimensions

A common mistake is to assume you can judge a Tanzanite's (or any gemstone's) physical face up appearance or size, based purely on carat weight.  We often hear a client mention that they have a 1 carat Diamond and want the same size Tanzanite to fit in a ring so they will be buying a 1 carat stone. This is not an accurate assumption, because of the simple fact that different gemstones have different densities (known as "specific gravity" in the trade). 

Ruby vs Tanzanite.jpg


A 1 carat Ruby, Tanzanite and Diamond on a gem tray illustrating different physical size but same weight


Some gem minerals are very dense like Sapphire and Ruby and others are not, like Diamond and Aquamarine. As a carat is simply a weight measurement, it does not tell you anything about the physical size of the gemstone you may be buying. The photograph above illustrates this well. 

To judge the size of a stone, always use the dimensions, particularly the face up dimensions to judge size. We include a useful Gem Dimension Chart on all our gem pages to help with this.





LIGHTING AND HOW IT AFFECTS TANZANITE


Tanzanite is very sensitive to light and this is due to the fact that it is trichroic. What this means is that a Tanzanite can look very different inside under incandescent (yellowish) light than it does outside in daylight. For this reason gemologists adopt a grading standard to make sure that when they are grading Tanzanites they are making a proper comparison. The grading standard for all colored gems and Diamonds is North Daylight Equivalent which is around 5,500 kelvin.

This video explains how Trichroism works and will give you a good understanding of why the different axes of color affect the way a Tanzanite appears to the eye under different lighting conditions.

 



Trichroism affects the way Tanzanite looks under different light sources and lighting conditions and gives rise to the "red flash effect" the stone is so well known for. This article goes into more depth on this.



TANZANITE PRICES & VALUE

Tanzanite's value in the different quality brackets translates into different price points with  the rarest grades commanding higher prices than the medium and lower grades. 

Color is the most important value factor and deeper colors command higher prices. Clarity also plays an important part and the closer to flawless a Tanzanite is, the more valuable. 

What is Tanzanite Worth?

A Tanzanite's value is very much dependent on its quality. Like all gemstones, quality is judged using the 4C's. The finest deeply saturated colors which are flawless command premium prices whilst pale stones or included (lower clarity) stones trade at much lower prices.

Prices can range significantly due to quality, from less than $50 per carat to upwards of $800 per carat. See our article on Tanzanite Prices to see a table of actual prices per carat prevailing in the market this year.


Is Tanzanite More Expensive than Diamonds?

Whereas Tanzanite is actually rarer than Diamond, its price is much lower. If you consider that a fine Diamond in a 5 carat size can range from upwards of $95,000 per carat whilst a very fine 5 carat Tanzanite will be in the $780 to $1,300 range (depending on where you are buying), it gives you a good idea of the disparity.


The Tanzanite market, unlike the Diamond industry is driven purely by the laws of demand and supply. The Diamond market is closely controlled by several large players who control the supply to the market and thus the price. 




WHAT IS THE LARGEST TANZANITE EVER MINED?

The largest tanzanite officially listed in the Guinness book of records and the world’s largest rough tanzanite was a 16,839 carat (3.38 kg, or 7.46 lb) stone mined by TanzaniteOne in 2005.

Worlds Largest Tanzanite.jpg
World's largest Tanzanite ever mined



HOW IS TANZANITE MINED?

Tanzanite, like most colored stones globally, is mostly mined by small scale "artisanal" miners. These are families or cooperative groups allocated a mining claim by the government and who collectively mine a small claim. One section of the mining area is mined by a multinational called Tanzanite One. This has caused conflict over the years and this article on "Small Scale or Large Scale Tanzanite Mining - which is more "Ethical" looks into this.




TANZANITE AS AN INVESTMENT

With fluctuating the state of the world economy in the past decade, Tanzanite has fast gained eminence as a tangible investment with great potential. We felt that we needed to make mention of this in this buying guide.

Tanzanite's unique set of economic indicators suggest that it may prove to be a good investment gemstone. This article covers this well Tanzanite as an Investment



TANZANITE HEATING - IS ALL TANZANITE HEATED?

This is a question we get asked very regularly. When researching Tanzanite many people are confused as to the role of heating in Tanzanite and whether it plays the same part as an enhancement as it does with gemstones like Sapphire where heating is used to enhance lower grade stones. 

This article goes into depth on the subject : Tanzanite Heating - The Facts




TANZANITE IMITATIONS, ENHANCEMENTS AND SYNTHETICS - WHAT TO WATCH OUT FOR

When purchasing Tanzanite, one of the most prominent concerns is whether what is being sold is genuine. It is important to attain a basic understanding of the pitfalls that exist in the market in this regard.

Where as Tanzanite has never actually been synthesized (lab created), a number of imitations and treatments, such as coatings do exist in the marketplace which any Tanzanite buyer must make themselves aware of.

This article looks at the basics to give you a good overview : Tanzanite Synthetics and Imitations




TANZANITE ORIGINS & HISTORY - Discovery and Lore


Tanzanite was discovered in 1967 in the foothills of Mount Kilimanjaro by Maasai tribesman. Legend has it that a bushfire that had swept the area had heated some surface lying gems which had turned them blue. The tribesmen spotted the blue sparkling stones as they herded their cattle through the area in search of grass.

Having no value to the Maasai, they were shown to a trader in the nearby town of Arusha called Manuel de Souza. Manuel originally thought the stone was a Sapphire and rushed up into the hills to claim the area but was puzzled by this amazing gem that sparkled pink and red within its deep blue color. He laid the very first claim but was unsure where to market this unknown gem material.

It was taken to New York and shown to Henry Platt, Chairman of Tiffany and Company and grandson of the founder
. Harry Platt immediately recognized this mysterious stone's potential, described it as "the loveliest blue gemstone discovered in over 2,000 years"  and named it after the country of its discovery. Tiffany & Company then negotiated to become its main distributor.

It launched Tanzanite onto the world stage with an unprecedented marketing campaign in 1968. Tanzanite became hugely popular in a very short time, even challenging the "big 3" Ruby, Emerald and Sapphire for dominance in colored gemstone sales in the US market.

Tiffany Co image JPEG.jpg

ABOUT THE AUTHOR Antony Zagoritis, Bsc, GG

Antony completed his GG (Graduate Gemologist) in 1998 at the Gemological Institute of America in California after a degree a Business at the University of Bath, in England. He has extensive experience in the colored gemstone trade with over 20 years buying rough at the source. He is currently the Ambassador to Kenya for the ICA (International Colored Gemstone Association) in New York which is the worldwide body for colored gemstones.

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