October 2019 Newsletter: Mexican Fire Opal


Mexican Opals are known for their vivid yellow, orange or orange-red colors. The intense color has earned this gem the nickname Fire Opal. Unlike precious opal, the Mexican Opal does not usually exhibit a play of color. But it makes up for this with its remarkable body color. It is the one of the few varieties of opal that can successfully be faceted, as some specimens exhibit considerable transparency.

Like other opals, Fire Opal is amorphous hydrated silicon dioxide by chemical composition. "Amorphous" indicates that opal has no crystalline structure; "hydrated" means that it contains water, typically from 3 to 10%. Opal is actually considered to be a kind of hardened jelly. But Fire Opal has some unusual characteristics not shared by other opals.

Opal is typically opaque and is cut as cabochons. Fire Opal is the only kind of opal that can be transparent to translucent, and you will often find the higher-grade Fire Opal cut in facets. People seeing these gems for the first time are often surprised to find out that they are opals.

The color range of Fire Opal can be can quite wide, and some pieces display multiple colors in a single stone. The brilliant sunny yellows are highly regarded, but it is the more saturated orange and orange-red which is especially valued. Indeed, among all the orange stones in the gemstone world, Fire Opal can display the most saturated orange.

Fire Opal is associated particularly with Mexico, and is mined in the Mexican states of Queretaro, Hidalgo, Guerrero, Michoacan, Julisio, Chihuahua and San Luis Potosi. The most important mines in Queretaro were discovered in 1835 and are still producing today. Small quantities of fire opal can also be found in Oregon in the USA and British Columbia in Canada.

See our collection of Fine Mexican Fire Opal



Notable Gems from the AJS Collection

This month we feature fine orange gems from our collection, including two new Mexican Opals along with Spessarite Garnet, Oregon Sunstone, Sphalerite and Citrine. Click on any photo to view the details for the gem.

3.43 ct Fire Opal from Mexico
3.43 ct Fire Opal from Mexico  [SOLD]
A gorgeous Mexican Opal oval in the vivid reddish-orange hue! This is very clean material with an intense color. At about 12 x 10 mm, this fine Opal will set up beautifully in a ring or pendant. Guaranteed natural and untreated.

5.18 ct Mandarin Spessartite Garnet from Nigeria

A top Mandarin Spessartite Garnet from the original deposit in Nigeria. This fine gem has a beautiful warm orange hue and is completely loupe clean. Mandarin Garnet of this color and quality are becoming increasingly rare and valuable. With wonderful brilliance and fire, this well-cut gem will sparkle in your jewelery design. Guaranteed natural and untreated.

See the video

11.79 ct Sphalerite from Spain
11.79 ct Sphalerite from Spain [SOLD]

An outstanding large sphalerite from the Aliva mine in northern Spain. This gorgeous round sphalerite is over 11 carats (13.53 mm) and is amazingly bright and fiery, with flashes of orange, yellow and green 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.

5.41 ct Sunstone from Oregon, USA

High quality Sunstone from the Spectrum Mine in southern Oregon. Great color with the distinctive schiller from tiny platelets of copper. Guaranteed natural and untreated, AJS Gem quality.

18.69 ct Citrine from Uruguay

An impressive golden-orange Citrine from Uruguay. This is beautifully clean material that has been precision cut in a trillion shape with portuguese faceting for maximum brilliance. Perfect for a unique pendant. Guaranteed natural and untreated.

See the video

4.65 ct Fire Opal from Mexico

4.65 ct Fire Opal Matched Pair from Mexico [SOLD]

A stunning matched pair of Mexican Opals in the vivid reddish-orange hue! This is very clean material with an intense color, beautifully matched, ready to set in your earring design. Guaranteed natural and untreated.


News from AJS and the Gems World

New Santa Maria Aquamarines

There was a lot of interest in the new Santa Maria Aquamarines featured in our September newsletter. We have just added more of these rare gems to our website, including a superb 7.72 ct pear, a 5.77 ct octagon, a 4.54 ct suite of 3 matched pears, and several matched pairs.

7.72 ct Santa Maria Aquamarine from Brazil 5.77 ct Santa Maria Aquamarine from Brazil 4.54 ct Suite of Santa Maria Aquamarine from Brazil

The finest Aquamarines in the world come from the Santa Maria de Itabira mine in Minas Gerais, Brazil. They are famed for their unusually deep blue saturation.

See our collection of Fine Aquamarine


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 am looking for a white or colorless gem (not diamond) which has a really pure white color (no tinge of yellow or gray). What would you recommend?  SE, Norway

We have done comparisons of a number of gem varieties that occur in white -- Sapphire, Zircon, Goshenite beryl, Danburite and Petalite.

Though examples of each of these varieties can occur in a pure white, we found that that high quality Danburite and Petalite consistently displayed a pure white with no tinge of a secondary hue. Though not well known, these are both reasonably hard gems that are completely natural and untreated and can be found in large sizes (5 to 10 carats) at very attractive prices.

See our collection of Fine Danburite

See our collection of Fine Petalite



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All the best in gems,

Ron, May & and Rung