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Opal & Tourmaline: October Birthstones

October has two birthstones: Opal and Tourmaline


Opals are formed as water seeps and flows through natural cavities in stone and fossil. The water absorbs silica from neighboring mineral deposits and the silica dioxide finds new homes in these crevasses. The spherical structure of the SiO2 forms elegant rows that develop into light refracting precious opals. Different parts of the world produce distinct opal characteristics, most notably Australia, where opal is the national gemstone. Ethiopia, Mexico and the U.S. also produce high quality opals.

Opal cabochons often contain some of the mineral matrix of the “host” stone. In other cases a precious cabochon is a liquidy light droplet of solid opal. Quality colorful opals too thin to stand alone in a setting are sometimes formed by hand into an opal “doublet” or “triplet”.  These stones are carefully attached to a strong stone under the slice of radiant opal.  In the case of a “triplet” a dome of clear quartz or synthetic clear epoxy protects the quality of the stone and magnifies the fire.

The more orderly the spheres of silica in the opal the more light and color is refracted and the more brilliant the color in the opal. This correlation of color and order can signify to the clarity of a higher self coming forth. These qualities can amplify ones inner peace and usher this tranquility into our actions.


Learning the nature history of a stone via internet search is a never ending story. In the case of tourmaline a search leads to the elegant scrolls and flourishes of Sinhalese written language. Tourmaline comes from the Sinhalese word “turmali,” (තුරමලි), roughly translated as “stone with mixed colors”. When I investigate these various gemstones for the Boulder Arts & Crafts Gallery Birthstone Blog Series, I assimilate the information and what is ultimately written is this synthesized record of fact and fancy.  Enjoy the blend and take what you will. Mostly, enjoy the stones for their colors, settings and your personal interpretations.

Tourmaline is formed by a mix of water and minerals that tends to fill the cracks in the magma as it cools and hardens into rock.

Black crystalline schorl tourmaline accounts for most the tourmaline in the world, but here we are interested in the sparkly multi-colored varieties. Watermelon tourmaline is green pink and white, can be faceted into beautiful banded gems and the beaded with threads and chains.

Whereas opals, above, are a non-crystalline silica, tourmaline is a excellent example of a crystalline silicate. The boron silicate structure in compounded with other minerals to give tourmalines their color and luminosity. The variety of tourmaline’s colors corresponds to the colors of the chakras or energy centers of the body. Colors of the stone can help to balance and benefit these centers.