Blue diamonds became popular because of the most famous so-called Hope Diamond. Natural fancy colored diamonds are very rare and expensive. Blue is one of the rare and most desirable colors. The Hope diamond, which is displayed in the Smithsonian Institution in Washington D. C. , is the most famous blue diamond in the world, and the largest at 45.52 carats.
The Hope Diamond, the world's largest deep blue diamond, is believed to be more than a billion years old. It is a doped semiconductor, formed deep within the Earth and carried by a volcanic eruption to the surface in what is now Golconda, India. Since the Hope Diamond was found in the early 1600s, it has crossed oceans and continents and passed from kings to affluent. It has been stolen and recovered, sold and resold, cut and re-cut. In the early 1800's, it was sold to King George IV of England. At the king's death (1830) his debts were so enormous that the blue diamond was likely sold through private channels. By 1839, the gem entered the well-known collection of Henry Philip Hope, and thereafter is now known as Hope Blue Diamond.
Natural blue diamonds are so rare that most jewelers have ever seen one. Quality for quality, fancy blue diamonds are more expensive than ordinary near-colorless ones.
Diamonds come in many shades, ranging from colorless, white, yellow and brown to more intense colors such as orange, pink, green and black. Of white diamonds the most valuable is the colorless gem, which is called a D color. The total range is from D to Z that is yellow. In colored diamonds, the higher the intensity of color and brilliance, the more valuable the stones are.
Like all other diamonds, blue diamonds are also valued based on carat, cut, clarity and color. There other diamonds colors like pink, yellow, black, brown and white are equally popular among gem lovers.