Blue Diamonds

• Blue diamonds are produced by tiny amounts of boron in the stone. The boron impurities cause only blue light to reflect off the stone, making it appear blue. The Hope Diamond, weighing 45.52 carats, is the most famous as well as the largest blue diamond in the world and is kept it the Smithsonian Institute in Washington, D.C.
  
  

Yellow Diamonds

• The presence of nitrogen in the molecular structure of a diamond causes a yellow hue. The most famous of yellow diamonds is the Sancy. It has been owned by French and English royalty and American society members and now resides in the Louvre in Paris.
  
  

Black Diamonds

• Black diamonds, also known as carbonado, are much older than their colorless counterparts. They are dated at 3 billion years old, whereas white diamonds are a youthful 1 billion. The black color exists due to the presence of graphite or iron minerals during the crystallization process. The Black Orlov Diamond is famous for its size (67 carats) and the mystery surrounding its origin.
  
  

Pink Diamonds

• Found only in Australia's Argyle Mine, pink diamonds are the rarest of all colored diamonds. They are also the most expensive. The cause of the pink color is not fully understood by gemologists. However, a theory exists that intense heat and pressure cause the normal molecular structure of the diamond to shift, causing light reflected by the stone to be seen as pink. Pink diamonds have become very popular in recent years since Ben Affleck gave Jennifer Lopez a large pink diamond engagement ring.