A diamond with color is the rarest of beauties

Any diamond is rare and unusual. The Diamond Information Center says that all the diamonds in the world -- engagement rings included -- would fill only a single double-decker bus.

That makes colored diamonds the needles in an already small haystack.

The mineralogy department at London’s Natural History Museum, currently staging “Diamonds: The World’s Most Dazzling Exhibition,” estimates that one in 500 to 10,000 gem-quality diamonds are colored.

“Colored diamonds are not for ‘regular’ people,” says Sally Morrison, director of the Diamond Information Center, which promotes the diamond industry. “They tend to be very expensive.... The rarest is red -- I’ve seen two of those in my life.”

Red diamonds, including the 5.11-carat Moussaieff Red on display in London, are worth $1 million or more per carat, according to Morrison.

Harvey Lieberman, the rough diamond buyer at jeweler Louis Glick, has been blown over by a few pieces of ice.

“Over the years, I’ve come across an intense blue diamond that really knocked my socks off ... ,” he says. “Also, within the last year I did a beautiful orange stone. I made a pear shape and I have done a heart shape on another. The pear was over 3 carats. Those are the pieces that I’ll remember forever.”

Anyone who has shopped for a diamond has probably heard about the 4Cs -- color, cut, clarity and carat. The same factors should be considered when purchasing a colored diamond, but more weight should be given to color and cut, he says.

All diamonds form the same way: as crystallized carbon. But, according to John King, laboratory projects officer at the Gemological Institute of America, colored diamonds usually are altered at the atomic level. An impurity in the lattice structure of the diamond creates the color; for example, if nitrogen is the invader, the diamond turns yellow, and boron would make a diamond blue.

Yellow diamonds, which mostly come from Africa, have been popularized by rap music stars. Jennifer Lopez is amassing a collection of colored diamonds, and Oprah Winfrey and Barbra Streisand also have many colored diamonds.

“Colored diamonds always have been treasured and valued because they’re special,” says Morrison. “They’re exclusive and elitist, but there’s been a recent interest in them by the general public because of Hollywood and the music industry.”