May 2016 Newsletter: Rare Gem Brazilianite

Our business has traditionally been in classic coloured gemstones like fine ruby, sapphire, spinel, topaz, garnet and tourmaline. But in recent years we've been adding some rare gem varieties to our collection, such as jeremejevite, grandidierite, cobaltocalcite, pezzottaite and cuprite. In this month's newsletter we look at our latest rare collector gem: Brazilianite.

Brazilianite was first discovered in 1944, though it was at first believed to be chrysoberyl. It was positively identified as a unique mineral in 1945 and named after its type locality in Minas Gerais, Brazil.

By chemical composition, Brazilianite is a hydrous sodium aluminium phosphate. It is one of very few phosphate minerals used as gemstones (the others are apatite and turquoise). Gem quality Brazilianite has excellent transparency and a vitreous luster, and it occurs in colors ranging from dark yellowish-green to a pale yellow. Brazilianite becomes colorless when heated, so a saturated color provides good assurance that the gem is unheated.

Brazilianite is medium-hard, with a hardness rating on the Mohs scale of 5.5, in the same range as apatite, scapolite and diopside. It is a fairly low density material with a specific gravity of 2.98; and a relatively low refractive index (1.621 to 1.623). Both density and refractive index are in the the approximate range of tourmaline. Brazilianite is a mineral in the monoclinic system with crystals that are elongated and prismatic.

Brazilianite is typically found in granite pegmatite and it is often found the cavities within the pegmatite where quartz, beryl and mica are also found. Brazilianite also found with tourmaline and feldspar.

Brazilianite may be confused with amblygonite, green apatite, chrysoberyl and yellow beryl. The State of Minas Gerais in Brazil is the largest producer. Brazilianite has also been found in the USA (New Hampshire), Canada, Argentina, France, China and Australia.

Recently we cut 2 beautiful Brazilianite gems from some very fine rough stone -- a lovely 3.74 ct (seen in the video above) and a huge 12.84 ct, listed below in our Notable Gems.

See our Rare Brazilianites

 

Notable Gems from the AJS Collection

This month we feature rare collector gems, including some special recent acquisitions.

Click on a photo to see the details for the item.

4.97 ct Color Change Garnet, Kenya

 
An exceptional large Color Change Garnet from the Taita Hills of southern Kenya. The best of this material has such a dramatic color change that it was thought to be alexandrite when first discovered. Clean gems over 2 carats are quite rare. This nearly 5 carat emerald-cut gem, found near the town of Wundanyi, is extremely clean with excellent transparency. It displays a very strong color change from a deep greenish-blue to a purplish-red. This rare collector's stone has been certified by the Gemological Institute of America (GIA), including a special Notable Letter, which notes that "the combination of the large size, color-change and high degree of transparency make this a notable gem."
 
9.48 ct Sphalerite, Spain

An outstanding large sphalerite from the Aliva mine in northern Spain. This gorgeous round sphalerite is amazingly bright and fiery, with flashes of orange and yellow as it is turned in the light. Beautifully cut and very clean, this is a superb gem sphalerite for your collection. Guaranteed natural and untreated.

See the video

1.12 ct Grandidierite, Madagascar
1.12 ct Grandidierite from Madagasdcar  [SOLD]
 
Grandidierite is very rare in gem quality, and transparent material is exceptionally rare, with most specimens under 1 carat. This 1.12 ct Grandidierite is a very special piece for the rare gem collector, for several reasons. It has a superb saturated blue-green color and exceptional clarity for grandidierite, which is typically opaque or, at best, with significant inclusions. This rare gem has been certified by GIA with a Notable Letter that describes this gem as "extremely rare" with "an appealing bluish green coloration." The GIA letter concludes that "the rarity of grandidierite makes this a notable gemstone." 
 

13.03 ct Cobaltocalcite, Spain

Cobaltocalcite is a rare variety of calcite colored by traces of cobalt. This gem is notable for its highly saturated color and superb translucency. This gem has an amazing glow when backlit. Gem-quality cobaltocalcites over 10 carats are very rare, especially in this vivid color. This fine specimen will delight the most discerning collector. Certified by GIA as natural and untreated, including a Notable Letter which states that "The large size, highly saturated reddish purple color and high degree of transparency makes this a notable cobaltocalcite." 

See the video

9.38 ct Gem Silica, Arizona USA

The finest Gem Silica comes from the Inspiration mine in Arizona. The best of this material is an intense turquoise color with very good translucency. This deep blue trillion is an extraordinary color that is rarely found. Guaranteed natural and untreated.

See the video

12.84 ct Brazilianite from Brazil

A rare gem Brazilianite in a very large size, nearly 13 carats. The color is a vivid yellowish-green with exceptional brilliance and excellent fire. This is fine transparent material, but there are some minor inclusions which are mainly visible only under magnification. This is an unusually large specimen that would be an important addition to any rare gem collection. Guaranteed natural and untreated.

See the video


News from AJS and the Gems World

  • Jubilee Ruby sells for $14 million at Christie's NY

A 15.99 ct Burmese Ruby, known as the Jubilee Ruby, sold for $14.2 million at Christie's New York auction on April 20th, making it most expensive colored gemstone ever sold at auction in United States. The oval ruby fetched a price of $885,866 per carat. The 25.6 ct Sunrise Ruby, which sold for $30.3 million at Sothetby's Geneva sale last year, holds the top spot for the world's most expensive ruby and most expensive colored gemstone.
 

  • Oppenheimer Blue Diamond Could Fetch $45 Million

On May 18th, Christie's Geneva will auction the 14.62 ct Oppenheimer Blue, the largest fancy vivid blue diamond ever offered at auction. Named for its one time owner, Sir Philip Oppenheimer of De Beers, the Oppenheimer Blue is an emerald-cut stone with elegant proportions. Though larger than the Blue Moon, a 12.03 ct cushion-cut diamond that sold for $48.5 million, the Oppenheimer Blue is not quite as clean, with a VVS1 clarity grade compared to IF for the Blue Moon. Christie's pre-sale estimate on the gem is $38 to $45 million.

 

 

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'm interested in the new chrysoprase from Australia that you featured in your March newsletter. Can you tell me what makes this chrysoprase so special? ER, UK

We recently purchased a parcel of top grade chrysoprase rough from an Australian miner and selected out the best of this material for cutting. The pieces we've cut have excellent color saturation with a vivid apple-green hue, and very good translucency that creates the wonderful luminosity that is charcteristic of the finest chyrsoprase. In addition, we cut this material very carefully to avoid any of the black inclusions which are typical of chrysoprase. It meant a low yield from the rough, but very high quality results. See our collection of Fine Chrysoprase.

 

What is the best location for amethyst? Are the ones from Zambia better than the South American stones? AC, USA

Zambia is justly famed for its highly saturated deep purple amethyst. The Zambian material tends, on average, to be higher quality than the Brazilian or Uruguayan amethyst, much of which is a pale violet or mid-toned purple. But having said that, there are very fine examples of saturated purple amethyst from South America as well, and our practice is to buy by quality rather than location. See our collection of Fine Amethyst.

 

 

 

All the best in gems,

Arnold, Rung & Ron

 

 
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