Home Gemstones Benitoite Value, Price, and Jewelry Information. By Joel E. Arem, Ph.D., FGA, Barbara Smigel, PhD. GG, International Gem Society. With dispersion higher than diamond and sapphire-blue body color, benitoite is one of the most attractive of all rare gems. Gem-quality crystals have been found only in San Benito County, California.Web