Ever since calsilica first appeared on the fashion jewelry circuit, it created quite a stir and generated a fair bit of controversy and speculation over it’s origin – particularly whether it is a naturally-occurring stone, or a man-made material. Whether used in a sterling silver pendant or in a necklace, calsilica made a big splash at jewelry shows!  After its initial appearance, the most persistent claim has been that the stone was found at a mine in the Mexican state of Chihuahua, in the veins or seams of the volcanic rhyolite at this location. Geologists have been denied access to the mine, supposedly to protect the resource from over-exploitation. More recent rumors have focused on an allegedly spectacular deposit of calsilica in China. At this time however, it remains just that – an unsubstantiated rumor!

Rainbow Calsilica is a synthetic stone that is manufactured from a mixture of calcite, plastic and artificial coloring pigments. The different colored bands through Rainbow Calsilica are powdered carbonate rock artificially colored and then stabilized with plastic. The bands of color can come in any color. Despite being a synthetic stone, Rainbow Calsilica has been increasing in demand for fashion jewellery. 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.

Perhaps the most telling report debunking the myth that calsilica is natural was published by the Swiss Gemological Institute (SSEF). SSEF reported that they had purchased two specimens at a mineral show in France in 2002. They tested a piece obtained in France, using Raman Laser Spectroscopy and it was found that the blue and yellow colors matched a man made pigment. They also said it had polymer and a paraffin-like substance. The supplier than claimed that they receive the material in the form of slabs directly from the mine in Mexico, and treat it with paraffin and resin to improve its resiliency. He does not however, address the presence of man-made pigments in the samples from France.

So where do we stand today? Based on all available information, it appears that calsilica is essentially an agglomeration of several natural and man-made materials including calcite and man-made pigments, held together by a paraffin-like binding agent. The original contention that calsilica was a form of microcrystalline calcite may be moderately accurate, but the coloring and binding agents are most likely man-made. Until the “mine owners” in Chihuahua provide greater access to the site, it would be wise to assume that calsilica is man-made.

Calsilica specimens can be quite beautiful and colorful, and as such, can be used too make earrings, silver pendants, rings, and other items. Calsilica can also be used as accents in a freshwater pearl necklace or other pearl jewerly.  While the purists amongst us may be disappointed that calsilica is man-made, calsilica continues to capture the imagination of jewelry designer as well as jewelry wearers alike.