The Birthstone Gemstone Called Opal

Opal has been revered for centuries by many cultures and is still considered a highly valuable gemstone today.

Ancient Arabs believed that this gem fell directly from the Heavens when lightening flashed. They believed that the lightning bolts gave it its fiery, intense colors.

Ancient Greeks held it in high esteem and believed that it could bestow gifts of prophecy to the wearer. It is also mentioned in Greek mythology in the story of Zeus defeating the Titans. Reportedly he was so happy with his victory that he wept tears of joy. When the tears hit the ground, they turned into opal.

What is it?

The name comes from the Latin word opalus, which means “precious stone”.

Opal is actually a form of non-crytalline quartz which is created in silica-bearing waters. When the silica gel hardens, this gemstone can be created. Six to ten percent of opal’s makeup is water. It is most often found near geysers or hot springs, but can occur in other environments as well.

The Birthstone Gemstone Called Opal

Different Types

There are several different types of this gemstone available today. These include:


This variety shows an intricate interplay of various colors that is commonly referred to as color play. This material is often very thin in nature and commonly displays colors of blue and green. The natural black opal is the most valuable of the precious varieties. When it displays colors of red and orange, its value is increased.


This type is named for its color rather than for the fiery flashes that the precious variety displays. The colors range from deep red to various shades of orange. It is even occasionally found in yellow. It generally contains little to no flashes of fire and is usually valued for its clarity and color. Most gem quality rough comes from mines found in Mexico.


The common variety (sometimes referred to as “potch”) is usually opaque and comes in colors of pink, milky white, gray, yellow, blue and green. It occasionally contains moss or is dendritic. Dendritic opal contains iron silicates that have been deposited into cracks.


Material without color play is very common and can be found all over the world. Pink and blue varieties are mainly found in Peru and are often sold under the name “Peruvian”. Other notable deposits have been found in Algeria, Chile and Bolivia.

Currently, Australia produces about 97% of the world’s supply of all types of gem material. The Coober Pedy and Lightening Ridge Mines are very important sources of the precious variety, also known as boulder opal. The Lightening Ridge Mines are where the majority of the black variety is found. Smaller deposits have also been mined in Honduras, Brazil and the Czech Republic.


Opals of all types have been synthesized for commercial sale. The two most notable producers of synthetics are found in Japan.

Most “synthetic” types on the market today would be more correctly termed “imitations” or “simulants”, since they contain substances not found in the naturally occurring type. For example, most simulated stones are filled with plastic stabilizers. Some vintage types are actually laminated glass with bits of colored foil mixed in.


Opals are weak due in large part to their water content. If they are allowed to dry out, cracking or crazing (small, webbed cracks) may occur. Keeping them in a tight plastic bag along with a damp cloth should prevent this in dryer climates. (It’s not usually necessary in wetter climates.)

They don’t necessarily mind being hot or cold, but they are highly sensitive to sudden temperature changes. Avoid cooking, cleaning and showering while wearing your opal jewelry. You should also avoid going from a warm house into a wintry day if your stone is not underneath a protective layer of clothing.

This gemstone only ranks between a 5.5 and a 6 on the Moh’s scale of hardness and tend to scratch easily. This makes them most suitable to earrings and pendants, as opposed to rings that tend to take more abuse. If you do choose to wear an opal ring, make sure that metal is surrounding the stone so that it can offer some protection. Rings will also require regular polishing to keep them looking their best.

Never use ultrasonic jewelry cleaners with your stones. Mild detergent, a soft cloth and luke-warm water should suffice for a thorough cleaning. Since opals are porous, you should never immerse them for any length of time in chemical or cleaning solutions. Even dishwater is a no-no, as your stone might absorb it.