July 2016 Newsletter: Black Star Sapphire from Thailand

Black Star Sapphire
from Thailand


It is well known that Thailand is the source of many of the world's finest colored gemstones. For gem dealers around the world, Bangkok is recognized as the place where colored stones of every grade can be purchased at the best prices.

But these days very few of the gems sold in Thailand are actually mined in Thailand. At one time Thailand was indeed an important mining center -- there were major ruby and sapphire mines in Trat, Chanthaburi and Kanchanaburi provinces, with historical references to the region's gemstone riches dating back to the 15th century. But by the late 1980's the Thai gem mines were largely exhausted. Today the gems cut and sold in Bangkok originate mainly from Africa, South America, Sri Lanka and Burma.

One of the last gems to be mined here is a gem unique to Thailand -- the black star sapphire with a golden star. These come from several mines in Chanthaburi province, but the supply is now coming to an end.

A question we are often asked about these unique gems is, Why do the black star sapphires from Thailand have a golden star? The answer is that these sapphires come from locales that yield yellow and golden sapphires, and the black star sapphires are actually golden sapphires that have a black body color due to inclusions of hematite. The gold star is the only vestige of the original sapphire color.

The Thai black star sapphires typically display a sharp 6 ray star under a focused light. But occasionally we find specimens with a 12 ray star and these rare stones are sought after by collectors.

Though the Chanthaburi mines are now only producing a trickle of material, we were fortunate to have invested in a significant supply of high quality material some years ago, and still have an excellent selection of sizes, ranging from 1 carat to over 50 carats. We even have quantities available in a number of popular calibrated sizes (such as 12x10, 11x9 and 10x8 mm), and you can choose the exact number of pieces you need. Finally, we have three rare 12 ray stars that will be of special interest to collectors. 


Notable Gems from the AJS Collection

This month we feature some some of our recent acquisitions.

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

4.07 ct Spessartite Garnet, Nigeria
A magnificent bright orange Mandarin Garnet. This is a brilliant gemstone with full luster and a remarkably vivid pure orange color. Cut with care and precision this bright stone is beautifully shaped and ready to be set into a wonderful piece of jewelry or brighten up your collection. We are sure that you will be pleased with this fine gem once you have received and seen it in person. Guaranteed natural and untreated.

1.08 ct Mahenge Spinel, Tanzania

1.08 ct Mahenge Spinel from Tanzania  [SOLD]
A an exquisite pink-red Spinel from Mahenge, Tanzania in a rare rectangular shape. This gem has amazing brilliance with a color that really pops. This gem came from the original find in 2007 and these neon colors have become treasured collector's items for those in the know. This superb spinel will make a gorgeous ring when set with diamonds in your design. Guaranteed natural and untreated.
5.45 ct Tanzanite, Tanzania

A deep violet-blue tanzanite in a hard-to-find emerald cut. Very clean material and beautifully cut to show off the wonderful color. This fine gem will make a stunning ring. Guaranteed natural.

See the video

5.34 ct Imperial Topaz Matched Pair, Brazil

A lovely pair of golden orange Imperial Topaz from Brazil. These well-matched gems are beautifully cut and very clean with excellent luster. These fine gems are perfectly sized for an elegant set of drop earrings. Guaranteed natural and untreated.

See the video

3.53 ct Fire Opal from Mexico

3.53 ct Fire Opal from Mexico  [SOLD]

A very fine Mexican fire opal in a vivid reddish-orange! Precision cut with excellent clarity, this hard-to-find round in a modified radiant cut will set up beautifully in your your jewelry design. Guaranteed natural and untreated


News from AJS and the Gems World

  • New! Special Value Gems from AJS

This month we introduce a new category of Special Value Gems. These are high quality stones from our regular collection offered at special prices. Take advantage of this opportunity to buy a fine gem of AJS quality at a very attractive price!

  • Spinel Declared a Birthstone for August

Jewelers of America and the American Gem Trade Association, who maintain the "official" list of birthstones, have added spinel as a birthstone for the month of August. Previously peridot had been the sole official birthstone for August.

The modern birthstone list was created in 1912 by the retail jewelers group now known as Jewelers of America. The list was first updated in 1952, adding alexandrite, citrine, tourmaline, and zircon as birthstones; and then in 2002, when tanzanite was made an additional December birthstone. The addition of spinel to the list recognizes spinel's value and importance in the gemstone market.



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.

Could you please clarify the ban on Burmese gems? Which countries have a ban in place? Does it affect all gems from Burma?  TP, Australia

The USA is now the only country we are aware of with restrictions on importing Burmese gems. The USA restrictions affect only ruby and jadeite mined in Burma (Myanmar). There are no restrictions on other Burmese gems, such as sapphire, spinel, peridot, zircon and moonstone. For more on the history of this issue see our article on The Ban on Burma Ruby and Jade.


I'm looking at white gems and wondering about the difference between danburite and petalite? Which one is a better stone?  JT, Canada

High quality Danburite and Petalite are both very good choices for white gems, and both have excellent transparency and a pure white color. Danburite is the slightly harder gem (7 on the Mohs scale, compared to 6 to 6.5 for Petalite), and has a slightly higher refractive index (1.630-1.626 compared to 1.502-1.518 for Petalite). But in fact it can be quite difficult to tell them apart.




All the best in gems,

Arnold, Rung & Ron