Blue diamonds are rarer and more expensive than white diamonds, according to How Stuff Works. Less than 1 percent of all diamonds are blue and they are rarely put up for sale.
The blue hue comes from boron atoms intermixed with the carbon atoms that makeup the diamonds. In April 2013, a blue diamond broke the world record for the price of a diamond per carat after it fetched $1.8 million per carat at an auction. The previous record was for $1.68 million per carat. Later, in Nov. 2013, the blue diamond’s record was broken by an even rarer pink diamond.