Of the 250 tons of earth that must be mined to obtain a single one-carat diamond, fewer than 20% of all diamonds that are mined are gemstone quality.  Most diamond gemstones are clear in color but 25-35% are fluorescent glowing blue, pink, orange, green, yellow, brown or a variety of those colors when they come in contact with ultraviolet light.  Even more rare, are the fancy-colored diamonds found only one in every 10,000.  Fancy-colored diamonds include the additional of a trace mineral that gives the diamond a visible color such as boron, which turns the diamond blue and nitrogen, which turns the diamond yellow.

Fancy Colored Diamonds

In the purest form, diamonds are colorless.  Though more rare than colorless diamonds, fancy-colored diamonds come in a variety of colors including

Red: Red diamonds are extremely rare, so rare in fact, that The Hancock Red, one of the world's most famous red diamonds, sold for $926,000. per carat at an auction in 1986.

Blue: Blue diamonds are also a rarity even among fancy-colored diamonds but are a little more known than the red thanks to the Hope diamond which was believed to be part of the crown jewels that were stolen in....and reappeared cut....The Hope diamond now resides at the Smithsonian Institution Museum of Natural History.

Pink: Pink diamonds are as rare as blue.  The largest pink diamond, the Darya-ye Noor Diamond, is part of the Iranian Crown Jewels and is estimated to be 182 carats.

Yellow and Brown: Though yellow and brown are the most common of the fancy-colored diamonds that's not to say they don't have their stand-outs.  Another diamond on display at the Smithsonian is the Portuguese diamond, a 127-carat yellow diamond.