Color Variations

• Blue diamonds obtain their color from the presence of boron. Not all blue diamonds are the same, however, as the hue varies greatly. The darkest blue diamonds are a deep blue, whereas the lightest are almost glacial in their pale blue radiance. The most desirable hue for a blue diamond is a deep blue, according to the website Precious Metals and Stones.
  
  

Enhancement Process

• According to AfricaGems.com, blue diamonds are enhanced by one of two processes. The HPHT (high pressure, high temperature) process involves subjecting the stone to extremes of heat and pressure, a procedure that alters its molecular structure, thereby changing its color. The more common method involves subjecting an off-colored diamond to low levels of radiation to alter its color to a more desirable hue.
  
  

Blue Diamond Lore

• The Hope Diamond, which resides at the Smithsonian Institute in Washington, D.C., is one of the world's best-known blue diamonds. The stone weighs in at 45.52 carats. The Idol's Eye is the largest known blue diamond; it weighs 70 carats.