Rainbow Calsilica – Myth Or Reality?

When calsilica first appeared on the fashion jewelry scene several years ago, it made quite a splash! With its bright, vivid, and varied colors, it is not hard to understand why calsilica captured the imagination of jewelry designer as well as jewelry wearers alike. Calsilica earrings, silver pendants, rings, and other items were often the stars at gem and jewelry shows.

So what is calsilica and where does it come from? The general consensus is that calsilica is a man-made amalgamation of various minerals and stone fragments that are held together with resin. Often, the powder and fragments are deposited under water and compressed to form cake. The cake is dried and infused with resin. Once the resin hardens, varies pieces are cut from the block, and then polished to achieve the desired sheen. Since calsilica is man-made there very well could be other processes used in its manufacture.

Although many claim that calsilica (or “rainbow calsilica” as it is sometimes called), is a naturally occurring material, there is little evidence to support this claim. The most persistent claim (and it still persists today!) was that calsilica was mined in Chihuahua, Mexico. Calsilica was allegedly discovered in the veins or seams of the volcanic rhyolite in the mine.

Calsilica was thought to be a form of microcrystalline calcite, with various clay minerals as the bonding agents. Supposedly, the mine in Mexico would send out letters of authentication and photographs of the mine. Now there are rumors of a spectacular deposit of natural calsilica in China. In 2003, the Swiss Gemological Institute ( www.SSEF.ch ) published a brief note on calsilica in one of their newsletters. SSEF purchased two specimens at a mineral show in France in 2002. The seller produced photographs of the mine in Mexico, along with a authentication letter from a US laboratory stating that the materials were not man-made. They found that the base white materials were indeed a calcite. However, they also found that man-made coloring pigments within the specimens. More importantly, SSEF found that the particles were bonded together by a transparent soft, plastic-like material that was very similar to paraffin wax.

The preponderance of the scientific evidence therefore indicates that calsilica is a man-made material. Nonetheless, good calsilica specimens are pretty, and can be used to make attractive, inexpensive fashion jewelry.