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Roger Weller, geology instructor

by Paige Lathrop
Physical Geology
Fall 2013

Treat Your Opals Right!

How to Correctly Care for the Precious Gemstone Opal

About Opals

Opals are beautiful gemstones that are quite unique. Only about a 5.5 - 6 on Mohs Scale of Hardness, opals are made up of very small, similar sized silica spheres and contain anywhere from 5-20% water (SiO2.nH2O). Because the silica spheres reflect light, they are what give the opal its radiant variety of colors and have a “rainbow-like iridescence” (

Ranging anywhere from red to white, opals truly are “the queen of the gemstones.”


Photo courtesy of R.Weller/Cochise College

In their rough, uncut state, also known as common opal, opals are not as magnificent.


Common Opals


Photo courtesy of R.Weller/Cochise College


Photo courtesy of R.Weller/Cochise College

Uses of Opal

            Most commonly, opal is used in jewelry. Opal can be set in earrings, necklace pendants, bracelets, and rings. It can also be fashioned into beads for bracelets and necklaces. Opal can also be used for carvings because of its soft composition.  



Opal Earrings


Photo courtesy of R.Weller/Cochise College


Opal Pendants

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Photos courtesy of R.Weller/Cochise College  


Opal Bracelets

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Photos courtesy of R.Weller/Cochise College


Opal Rings

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Photos courtesy of R.Weller/Cochise College


Opal Beads

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Photos courtesy of R.Weller/Cochise College

Opal Carvings

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Photos courtesy of R.Weller/Cochise College


Problems With Opals

As stated above, opals contain water. Because of this water content, paired with their already soft composition, opals can be difficult to care for. Dry, arid regions can cause opals to crack, basically ruining the gemstone.

            Opals are also very heat sensitive and are not particularly durable. Rapid change in temperature can shock the opal, causing it to crack or break. It is not recommended that opals, when used in jewelry (rings, bracelets, sometimes necklaces), be worn in places where they could be especially susceptible to damage.



Cracked Opal Ring

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Photo courtesy of

            It is highly recommended that one removes any opal jewelry before doing any sort of activity that could harm the gemstone.

            Opals are soft and can scratch very easily. When used in jewelry, there must be a special setting (shown below) for the opal, and the opal must be polished on a fairly regular basis to keep the appearance shiny and the surface protected.

Description: Opal Jewelry Gemstone Information op26

Photo courtesy of

            However, if one takes good care of opal, it will remain beautiful and dazzling.

Polishing Opal

            Once an opal has been cut to the desired shape and size, or if the opal is being repolished, a polishing agent and a felt wheel are key. A common polisher for opal is cerium oxide, which helps bring out the shine in opal and protects it.

A felt wheel is used to safely and gently rub the polish into the opal without scratching or damaging the opal’s surface.

The following video shows the process of cutting, shaping, sanding, and polishing an opal cabochon. The end of the video shows the cutter polishing the opal on a felt wheel with polisher already on it.


*Though it may look relatively simple, I’d suggest leaving this process to the professionals…you don’t want to end up with a damaged opal!

Cleaning Opal

            Cleaning opal is a vital part in maintaining its exquisiteness and longevity. Dust, dirt, and other unwanted particles can breakdown the polish of the opal, scratch it, crack it, or sometimes even lift the opal out of its setting, which can be very detrimental to the gemstone.

            When cleaning opal, it is not a good idea to use rough abrasive material like sandpaper. This can scratch the opal and wear down the surface.

The suggested cleaning steps below can ensure opal’s safekeeping:

1.    Start with warm water. Use warm because hot water can crack the opal and so can cold water.

2.    Place the opal into the water and add a few drops of mild soap.

3.    Gently swirl the opal around in the water.

4.    If the opal is set with other stones, use a soft toothbrush to gently clean them, but do not brush the surface of the opal (it can scratch the surface).

5.    Rinse the opal, removing any excess soap.

6.    Use a soft cloth to dry the opal, or allow the opal to air dry.


Storing Opal

            When opal is not being worn, keeping it in a soft, dry cloth bag or case is a good idea. This will prevent it from being scratched. If the opal is being stored for a long amount of time, place a damp piece of fabric in a sealed bag with the opal- this maintain the moisture level and will keep the opal from drying out.

            NEVER keep opals in places where the temperature could fluctuate rapidly. As stated before, this could jolt the opal and cause it to break and/or crack. This means that storing opals in attics, basements, or near windows is not an ideal location.



Works Cited