July 2018 Newsletter: Grading Tanzanite

Tanzanite, a rare violet-blue form of the mineral zoisite, was first discovered in 1967 in Tanzania. East Africa remains the only source for this gem. While there is a steady supply of Tanzanite in the market, the availability of high grade material is limited.

The color of the best Tanzanite is quite unique in the gemstone world, rivalled only by fine blue sapphire. But not all Tanzanite is especially valuable. Indeed you will find a wide range of prices, from below $100 a carat to over $1,000 per carat. The main determinants of Tanzanite value, like all colored gems, are color, clarity, cut and carat weight. But in the case of Tanzanite, color is so important that it outweighs almost all other considerations.

Tanzanite is classified as a Type I gemstone by GIA, meaning that Tanzanite specimens are normally eye clean or better. So clarity is usually not a problem. But the saturation and tone is highly variable, with colors ranging all the way from pale lilac to midnight blue. (Note that there are also other colors in Tanzanite, including gold, green, brown and pink. These are properly referred to as Fancy Zoisite, since the term Tanzanite, strictly speaking, refers to the violet-blue or bluish-violet colors of zoisite).

Deep Blue Tanzanite Blue Tanzanite Violet Blue Tanzanite
Top Grade Tanzanites

Given the price variation, it is important for buyers to understand Tanzanite grading. The first thing to know is that there is no official grading standard in the trade. This may come as a surprise, since you will often hear people talk about "AAA Tanzanite". But this term has no real definition in the gems trade. Indeed, the largest miner of tanzanite, a company called TanzaniteOne, has proposed a completely different grading scheme through their non-profit subsidiary, the Tanzanite Foundation. They grade color using terms like "exceptional", "vivid", "intense", "moderate", "light" and "pale," and grade color as "violetish blue" or "bluish violet."

Taznaite Grading

Though grading terms like vBE and bVM are not commonly used in the gem trade, this chart does succeed in capturing the basic principles of Tanzanite grading. In general we can say that a tanzanite is more valuable if the color is more blue than violet, and when the color is deeper or more saturated. Though some buyers may prefer a more violet color, or a lighter tone, the deep blue tanzanites will sell at the highest prices in the market.

See our collection of Fine Tanzanite



Notable Gems from the AJS Collection

This month we feature some impressive new acquisitions, including Pink Tourmaline, White Sapphire, Aquamarine and Tanzanite. Click on any photo to view the details for the gem.

12.63 ct Pink Tourmaline from Nigeria
A marvellous Strawberry Pink Tourmaline in a very large size. This is beautifully clean material with wonderful saturation, custom cut in an elegant cushion. This impressive gem will set up beautifully in your jewelry design. Guaranteed natural and untreated.

5.16 ct White Sapphire from Madagascar

A stone cold beauty, with the true look and brillance of ice. No other white gem could look better. A glittering white sapphire in a perfect ring size. Guaranteed natural.
25.65 ct Aquamarine from Brazil

A splendid trillion Aquamarine in a very large size! Trillion cuts have amazing fire, and this striking Aquamarine is no exception -- this is a bright and fiery gem that will make an impressive pendant. Guaranteed natural and untreated.

See the video

9.22 ct Spessartite Garnet Set from Nigeria

We have carefully matched fine spessartites from our collection to put together this unique earring set with blue sapphires and diamonds. The two pairs of spessartite ovals are 4.15 cts and 2.74 cts respectively, while the heart-shaped pair is 2.33 cts total. The 2 white diamonds are 0.12 ct total weight while the round blue sapphires are 0.19 ct.

8.29 ct Tsavorite Garnet Cabochon from East Africa

8.29 ct Tsavorite Garnet Cabochon from East Africa  [SOLD]

Terrific Tsavorite Garnet cabochon fashioned in a sugar loaf! Nice translucent material with wonderful color, big size. This impressive gem will set up beautifully in a ring or pendant. Guaranteed natural and untreated.

14.19 ct Tanzanite from Tanzania

A superb deep blue tanzanite over 14 carats in a hard-to-find round shape! This gorgeous gem has a rich sapphire-blue color that is rare in tanzanite. This gem has been precision cut to bring out the full potential of this beautifully clean material. Guaranteed natural.

See the video

News from AJS and the Gems World

De Beers Surprises by Entering the Market for Synthetic Diamonds

De Beers Lab Grown Diamonds

De Beers, the world's leading miner and trader of natural diamonds, had vowed for years that they would never sell lab-grown diamonds. Now the company has surprised the industry by introducing a line of jewelry made with synthetic diamonds.

The new lab-grown brand, to be called Lightbox Jewelry, will sell white, pink and blue synthetic diamonds up to 1 carat for $800 per carat, far below current prices for lab-grown diamonds. The diamonds will be sold only as jewelry, not loose. A De Beers executive noted that "We don’t think synthetics should be priced as inherently rare or precious things." The company is specifically not targeting the engagement market. In fact, its initial product line doesn’t include rings, only earrings and pendants, though it’s possible rings will be added eventually.

De Beers is investing $94 million in a new production facility in Oregon that will eventually produce as much as 500,000 cts. of lab-grown diamonds a year, which will translate to 200,000 cts. of polished stones.

Industry analysts see this as a strategic move by De Beers to create more distance between natural diamonds and synthetics, relegating lab-grown diamonds to the category of fashion jewelry, similar to what has happened to synthetic sapphire and ruby.



Ask the Gem Experts

Each month we answer questions from our customers. We welcome your questions and you can submit a question from our contact page.

I just loved Meghan Markle's aquamarine ring that you showed in your recent newsletter. Do you have any gems in that color and shape? Are they expensive? MT, Canada

The Duchess of Sussex (as Ms. Markle is now known) wore an emerald-cut Aquamarine set in a gold ring with small diamonds on the band. The ring was reportedly made for Princess Diana by Asprey of London. The size of the Aquamarine was not disclosed, but it appears quite large, likely over 20 carats.

We do have two very similar Aquamarines in our collection, a 15.90 ct and a 19.87 ct. Both gems are from Brazil, completely loupe clean, untreated, and precision cut. They are both a very fine color, and quite affordable given their large sizes.

Click on the photos below to see details and videos:

19.87 ct Aquamarine from Brazil 15.90 ct Aquamarine from Brazil
19.87 ct Aquamarine   15.90 ct Aquamarine



All the best in gems,

Arnold, Rung & Ron