Red hot. Fiery orange. Sunshine yellow. Red, orange, and yellow gems can evoke images of heat and flame. Some even have trade names that fit their fiery natures: flame opal, in which ribbons of red play-of-color race across the surface of the gem; fire opal, with its vivid, saturated reddish-orange hue; and flame spinel, a fiery orangish-red. Not every red, yellow, and orange gem produces spectacular fiery colors—only a few from certain localities do. Some commercially available gemstones, such as yellow sapphire and orangey-yellow spessartite, may have the right hue, but they don't have the right stuff—they're just not hot. Gem varieties such as citrine (yellowish-orangey quartz) and heliodor (golden or greenish-yellow beryl known as "gem of the sun") also fail the flame test. Spessartite is one of the gem varieties that differ from one locality to another. The "Little Three"