A distant relative of the spodumene family, diopside is found in various bright colors, most commonly emerald-green, but also a lighter green resembling tourmaline and a violet-blue. (Chromium, iron and magnesium content determine the gemstone's color.) Mined in Myanmar, India, Brazil, parts of Africa, Russia, and the United States (especially New York). Beautiful but not often used in jewelry because of its low rating (5.5) on the Mohs hardness scale.