Gem Profile- Common Opal

Almost everyone recognizes the "play of color" or "color flash" in precious opal, which is relatively rare. What many don't realize is that opal as a rock is actually quite abundant.

Material with the same mineral composition as precious opal but without any play of color is called "common" opal.

Glassy, brittle, and often opaque or occasionally translucent common opal can be found worldwide.

Some pieces are attractive enough to be used as gem-rocks.

Plain, common opal can be found all over the world.

As discussed in our Opal Introduction, opal often fills cracks, seams, vugs, and voids in matrix rocks.

Because it forms near the earth's surface at relatively low temperatures in areas of volcanic activity, opal is frequently found as nodules within solidified volcanic ash, or pumice.

A notable example is Mexican "jelly" opal, a common opal found in volcanic matrix.

Transparent to translucent specimens in bright yellow-orange to cherry red are called "cherry" or "fire" opal named for their color, not because they contain actual fire.

Jelly opal is less brittle than other opals, and clear, brightly colored pieces are often faceted into gemstones.

Cabochons are usually small since the opal forms in pumice vugs. When play of color is present, they are called "Precious Fire Opals."

Jelly opal in matrix is also used for small carvings animals, plants, and sea creatures where the opal highlights part of the subject. Clear opal with little or no color is called "water" or "crystal" opal.

Jelly opal occurs in white, yellow, green, and blue and is found in nine Mexican states.

A few commercial mines exist, but most material today is hand-dug in open quarries and transported to market by burro.

Mexican jelly opal, or fire opal, cut and wrapped in 21-gauge gold filled wire by Beverly Brown

Mexican fire opal cabochon, made into a wire ring by Dale Cougar Armstrong.

The term "common" also refers to the opal that comes to us from South America, known as "Peruvian Opal." Although this lapidary material has absolutely no play of color, its delicious variety of colors in blues and pink make wonderful cabochons and beads for the jewelry making industry. Peruvian Blue opal is only mined in one location in the Andes Mountains and it is the national stone of Peru.


This stone might be a Andean Blue Opal from Peru, although it resembles dyed chalcedony with inclusions. The stone is beautifully wire wrapped in a reversible pendant by D'Arcy Johnson.

The most sought-after and rare "Peruvian Blue" is a translucent gemstone that commands high prices.

More common is the opaque blue opal, often showing swirls of white and sometimes hints of pale teal or green, colored by copper. Because it is less expensive, this common Peruvian blue opal is usually made into beads and is sometimes dyed to enhance its color.

To check if your blue opal beads have been dyed, look for uneven color. Plain white common opal can also be dyed blue or pink, often showing similar uneven tones.

If a strand of beads is advertised as "natural" Peruvian blue or pink opal and priced around $40 or less, it is likely counterfeit.

As a designer, I personally prefer the natural artistic swirls and color variations found in genuine, common Peruvian blue opal.

Common Peruvian blue opal rough and cabochons, showing both opaque and translucent areas, with artistic value! Private collection, Dale Armstrong

As a wire artist, I am known for working mainly with natural earth tones and shades of green. However, I do like one pink stone: Peruvian Pink Opal.

The luscious raspberry to pale pink color of this opal gem is completely natural. It comes from the same area in Peru as the blue material, but the mineral content contains iron, which gives this opal its pink hue.

Sometimes strands of beads are dyed to enhance their color, but pink opal is very affordable and can also be purchased as cabochons.

Dyeing chalcedony is the main imitation of either blue or pink opal in cab form.

Beware of products labeled as "Peruvian" or "Andean Opal Chalcedony."

Rough and unpolished slabs of Peruvian pink opal. The rough on the back left was photographed wet to show what it will look like when it has been polished. Private collection, Dale Armstrong.

There are many other names for common opal, usually based on the locality or its color.

Some examples include "Nickel" opal, a gorgeous green colored by nickel found in Poland, and Tanzania material, which is a beautiful green resembling chrysoprase called "Prase" opal.

Brazil and several North American locations produce opal with fern-like dendritic inclusions, known as "Dendritic" opal.

Common opal is found all over the world, with notable locations including New Zealand, South Africa, and various regions across the United States.

Dendrite opal from Burro Creek, Arizona. Private collection, Dale Armstrong.