July 2020 Newsletter: Varieties of Quartz

 
Amethyst Gem Silica Madeira Citrine Chrysoprase
 

Quartz is one of the most common minerals on earth, second only to feldspar. In fact Quartz makes up about 12 percent of the land surface and about 20 percent of the Earth's crust.
 
Quartz has been prized as a gemstone since antiquity because of the wide range of colors and the fact that it has excellent hardness and durability, allowing it to polish well. It also has many industrial uses, in electronics, glassware, optics and as a crystal ocsillator in clocks.
 
All Quartz is silicon dioxide by chemical composition with a hardness of 7 on the Moh's scale. But the different Quartz minerals are characterized by different size crystals.
 
Macrocrystalline Quartz have large crystals that are recognizable by the naked eye. They are typically transparent to translucent and gem quality specimens are usually cut with facets. Examples include amethyst, citrine, ametrine, rock crystal, rose quartz and smoky quartz.
 
Cryptocrystalline Quartz (sometimes called Microcrystalline) have microscopically small crystals. These are often referred to as varieties of chalcedony, and are typically translucent to opaque and are usually cut as cabochons. Examples include chyrsoprase, gem silica, carnelian, bloodstone and jasper.
 
Citrine Pendant Citrine Pendant back   Amethyst Pendant Amethyst Pendant back
Citrine Pendant in Yellow Gold   Amethyst Pendant in White Gold
 
Though gem-quality specimens of Quartz are rare when compared to the ubiquity of the mineral, gem Quartz is nonetheless quite inexpensive. You'll find that Quartz varieties are often cut in large sizes for maximum color, so they tend to be especially suitable for pendants.
 
The rarest Quartz is Gem Silica, a cryptocrystalline variety colored by traces of copper. Fine specimens display a vivid bluish-green color with excellent translucency.
 
Amethyst has historically been the most popular of all Quartz varieties. At one time Amethyst was quite a rare gem, and as recently as the early 19th century it was regarded as one of the five cardinal gems, along with diamond, emerald, ruby and sapphire. Then very large desposits were found in South America, making Amethyst widely available.

 

 

Notable Gems from the AJS Collection

This month we feature some of the finest Quartz gems from our collection. Click on any gem for details.

31.25 ct Amethyst from Brazil
An outstanding deep purple Amethyst from Brazil in an elegant pear shape, over 26 mm in length. This is completely clean material with excellent brilliance that will make a stunning pendant. Guaranteed natural and untreated by AJS Gems, Bangkok.
 

21.90 ct Madeira Citrine from Uruguay

A very fine Madeira Citrine over 20 carats with a rich, open color. Expertly fashioned in a portuguese cut for maximum brilliance. Completely loupe clean. Guaranteed natural and untreated.
 
 
5.47 ct Gem Silica from Inspiration Mine, Arizona

A rare Gem Silica from the famous Inspiration Mine in Arizona. Excellent color saturation with nice translucency. It's rare to find a Gem Silica of this quality in a round shape. At 10.60 mm in diameter with a high dome this fine gem will set up beautifully in a ring or pendant. Guaranteed natural and untreated.

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22.00 ct Ametrine from Bolivia

A very fine gem Ametrine from the Anahi Mine in Bolivia. This is beautifully clean and transparent material with excellent color separation, with well-defined regions of saturated amethyst and madeira citrine. At over 20 carats, this is a first rate specimen for the collector, at a very affordable price. Guaranteed natural and untreated.

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55.94 ct Chalcedony Suite from Africa

Three beautiful African Chalcedony gems, well matched for color, size and shape. At 18 mm in diameter for each gem, this unusual suite is ready to be set in your jewelry design. Guaranteed natural and untreated.

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35.92 ct Chrysoprase from Australia

A large Chrysoprase cushion from Australia, over 35 carats! Vivid apple-green color with excellent consistency, this impressive gem displays very good translucency with a distinctive glow. Guaranteed natural and untreated.

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News from AJS and the Gems World


20% Discount on All our Gems for the month of July!

As the world continues to emerge from the persistent Covid-19 pandemic and international airmail service is still disrupted, we are offering a 20% discount on all the gems in our collection.
 
Take advantage of this terrific offer to buy the gem you've always wanted!

Use this discount code at checkout:  JULY-20
 
 

Small Scale Tanzanian Miner Becomes Overnight Millionaire
 
Tanzanian Miner Becomes a Millionaire

A small scale Tanzanian miner, Saniniu Laizer, became a millionaire overnight by selling two Tanzanite gemstones he had mined — the largest ever found in the country — for $3.4 million, according to a report by the BBC. The stones weigh 9.2 kg and 5.8 kg.
 
Laizer, reportedly a father of more than 30 children, told the BBC that he planned to use the money to build a shopping mall and school in his community in Simanjiro. He said the windfall would not change his lifestyle, and that he planned to continue looking after his 2,000 cows.
 
Most Tanzanite mining is carried out by large companies, but some small-scale miners like Mr Laizer acquire government licences to prospect for Tanzanite. Illegal mining is prevalent especially near mines owned by big companies. In 2017, President Magufuli ordered the military to build a 24 km perimeter wall around the Merelani mining site.
 
 
 
 

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.

Can gemological labs identify origin for any gemstone? Can they tell which region or mine the gem came from?  JB, Canada

Origin identification is a fairly recent development in lab reports for colored stones. Leading gemological labs such as GRS, GIA, AGL, Gubelin and SSEF now offer country of origin identification for certain gem types, usually only ruby, sapphire, emerald, red spinel, jade, alexandrite and paraiba tourmaline. The science behind these identifications is based on the pioneering work of Dr. Edward Gubelin, whose lifetime work was the study of gemstone inclusions.
 
It is still an evolving science, however, and different labs may disagree on the origin of a particular gem. The lab reports tend to use fairly careful language in stating their opinion on origin and will state the country (and occasionally the region) but not the specific mine.
 
 
 
 
 
 

All the best in gems,

Ron, May & and Rung