September 2020 Newsletter: Cabochon Gems


In the long history of gemstones, faceted gems are a relatively recent innovation. Gems were not cut with multiple faces in a geometrical pattern until the invention of the horizontal cutting wheel in the 15th century. Prior to that, gems were mainly fashioned as cabochons, a smooth domed shape with a flat base.

Even though most fine gemstones are now faceted, cabochons (or "cabs" as they are called in the trade), are still popular. You will find them mainly in varieties like Moonstone, Opal and Chrysoprase, as well as in Star Sapphire, Star Ruby and Chrysoberyl Cat's Eye.

Faceted gems have superior brilliance and fire, because they maximize the light that is returned to the eye. But cabochons maintain their popularity for several reasons. In the case of so-called phenomenal gems, such as those that display a star or cat's eye, the gem will only display the interesting optical effect when cut as a cabochon.


Blue Star Sapphire Ring Moonstone and Tanzanite Pendant Burma Jadeite and Diamond Ring
Blue Star Sapphire Ring Moonstone and Tanzanite
Burma Jadeite and
Diamond Ring

In other cases, some gems are cut as cabochons because they are opaque or translucent rather than transparent. Faceting this material does not produce very good results. You will also see lower grade material in gemstones such as Sapphire, Ruby, Quartz and Garnet cut as cabs. If the gem material has very good color but is not sufficiently transparent or clean to be faceted, it can still be shaped and polished to be a very attractive cabochon. Some rare gems, such as Gem Silica and Rhodochrosite, are usually cut as cabochons.

From time to time customers who are fond of cabochons ask us for a high quality Sapphire or Ruby cut en cabochon. These are difficult to find because facet-grade material is almost always faceted instead. The reason is simply one of economics. A high quality transparent sapphire will sell for a higher price if faceted. Only lower grade material, known as "cabbing rough" in the trade, will be cut as cabochons. For the highest quality cabochons, look for Star Sapphire and Star Ruby, as well as Jadeite, Opal, Chrysoprase and Gem Silica. For in these gems the very finest stones will be cabochons.

Notable Gems from the AJS Collection

This month we feature some fine Cabochon gems from our collection. Click on any gem for details.

2.82 ct Burma Jadeite
A lovely Imperial Burmese Jadeite Jade gemstone. This gem is a fine emerald green color with vivid intensity, smooth polish and an elegant oval shape. Precious Jade of this quality is both rare and valuable indeed. This gorgeous gem is completely natural and untreated and comes  with a certificate From The Gem and Jewelry Institute of Thailand (GIT), certifying it as "A-Jade".

19.87 ct Ethiopian Opal

A top Opal from Ethiopia in a very large size, nearly 20 carats (about 20 x 16 mm)! This fine Opal has excellent translucency and play of color, and will make an impressive pendant or cocktail ring. Guaranteed natural and untreated
23.29 ct Rubellite Tourmaline set from Nigeria

A well matched suite of Rubellite Tourmalines in cascading sizes. These will make an impressive set of drop earrings. The total carat weight is 23.29 carats. Each of the 3 pairs is also available individually to interested buyers, please contact us for more information. Guaranteed natural and untreated.

See the video

14.75 ct Gem Silica from Inspiration Mine, Arizona

14.75 ct Gem Silica from Inspiration Mine, Arizona  [SOLD]

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 bright and vivid fancy cabochon is an excellent example, with a unique shape perfect for a stunning pendant. Guaranteed natural and untreated.

6.35ct Trapiche Emerald Set from Colombia

Traphiche Emeralds are very rare, but a matched set of round Trapiche Emeralds is beyond rare! These stunning pieces are highly translucent with well-defined radial arms. The individual gems are about 8 mm each, and will set up beautifully as a set (earrings and a ring or pendant) or a multistone jewelery design.

See the video

15.16 ct 12 Ray Black Star Sapphire from Thailand

15.16 ct 12 Ray Black Star Sapphire from Thailand  [SOLD]

A rare 12 Ray Black Star Sapphire from Thailand. This unusual gem displays a sharp and well-defined double star against a lustrous black body color. A very impressive stone for the rare gem collector. Guaranteed natural by AJS Gems, Bangkok.



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. 


What has been the effect of Covid-19 on the gem and jewelry trade? Has it impacted your business?  JT, Canada

I think it's fair to say that nearly everyone's life has been affected by the Covid-19 pandemic, and the gem industry is no exception.

Because of the limitations on international travel, dealer trading has been limited and this has affected the supply chain with very little new material entering the market. Retail jewelry shops have had to close for significant periods in many locations, and some businesses may never recover. With a challenging economic environment, gold prices have reached record highs.

We consider ourselves to be fortunate since Thailand has been very successful in controllling the spread of the virus, with no community transmission here in more than 3 months. Since we sell online, our operations have not been interrupted, though postal disruptions have required us to use courier services for all our shipments.

Since we have a large inventory we haven't been too affected by issues with the supply chain. In fact we have quite a bit of gem material that we are still processing. In next month's newsletter we'll announce some fabulous new Pink Morganite from Brazil, some of the finest we've seen.



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All the best in gems,

Ron, May & and Rung