Prehnite’s bright, almost luminescent, swirling green colors (reminiscent of Jade), mesmerizing clarity and striking luster, make it an extremely attractive collector’s gem. In his book, “Gemstones of the World,” Walter Schumann describes Prehnite as a transparent to translucent gemstone, which accounts for its “cloudy” appearance. This is totally normal and like many gemstones, its distinctive appearance is key to its appeal. While its main colors are a range of pleasant greens that are often unique to Prehnite, yellow, gray, colorless or white varieties also exist. Prehnite has some interesting common names including “grape jade” (in China it is called “putao yu,” meaning grape jade, due to crystal formations that look like a bunch of grapes), “cape emerald” (for the location of its discovery and visual similarities to Emeralds) and “prediction stone” (see above). Prehnite is usually found in cavities along fractures of basalt. The Australian deposits occur in scattered outcrops of Antrim Plateau Volcanics of early Cambrian age (about 570 million years old) and consist of massive basalt up to 197 feet thick. Although the primary Australian deposits cover thousands of square miles in the east Kimberley (Western Australia) and the adjoining Northern Territory, gem quality Prehnite is very scarce. With about 90% of the world’s reserves of this beautiful green gem, most of the Prehnite you’ll see on GemsTV hails from Australia.
Due to its glassy luster Fluorite is highly coveted. Fluorite is the natural crystalline form of calcium fluoride and often forms beautiful cube-shaped crystals. It is a transparent to translucent mineral. When pure, Fluorite is colorless; however, it usually contains impurities that color it. The most common colors are violet, blue, green, yellow, brown, pink and bluish black. Arguably, the most popular color for Fluorite is a deep purple that can rival Amethyst in its finest examples. Indeed Fluorite/Amethyst comparisons are often used to show that color cannot be relied upon as a gemstone identification test. An eye catching phenomenon of Fluorite is its distinctive multicolor banding. Chunky Fluorite bead strands optimize this exceptional effect. Interestingly, the “blue john” variety mined in England that possesses curved bands of blue purple, violet, yellow and white has been used as an ornamental gem since Roman times. Color Change Fluorite is mined in Bihar, India and shows a dramatic change from green to purple. Color change gems are those that distinctly change their color when viewed under two different light sources.