genuine rainbow moonstone sterling silver pendant necklace. The moonstone is 14 x 10 mm in size and weighs over 5.75 carats Select either a 20 or 18 inch 1.3 mm double rope sterling silver chain or pendant only comes with black velvet gift box Moonstone is the most famous member of the feldspar group. Technically, moonstone belongs to the orthoclase branch of the feldspar family and rainbow moonstone belongs to the labradorite branch. Moonstone's floating light that appears to emanate from within is known as adularescence. It is caused by structural anomalies within the stone, which refract or scatter incoming light. The size or thickness of these anomalies determines the color of the floating light. Moonstone is found in Sri Lanka, Myanmar, Madagascar, Brazil, Australia and India. The various colors only come from India and the other sources yield white moonstone. In India, rainbow moonstone is mined in the southwest and blue is mined at Bihar in the center of the country.