Most people call a diamond's shape "cut." Since January 2006, however, the Gemological Institute of America (GIA) started using the term to refer to the quality of a round polished diamond's workmanship, known as Cut Grade.
Cut Grade considers the workmanship in transforming a diamond from rough to polished. It is the only characteristic of a diamond determined by human action.
Pink, blue, green, red or other naturally colorful diamonds are Fancy Color or Colored diamonds. They are very rare creations of nature and the majority of them - more than 85% of the fancy color polished diamonds - are fancy yellow diamonds smaller than 1 carat.
Horse Head
When we talk about unusual diamond cuts, the Horse Head is one that a surprising number of people are familiar with. The shape was invented by Henri Daussi Loots, an Antwerp master diamond cutter, founder of the New York based jewelry company that still bears his name. The Horse Head is more common than one might expect and GIA even has a 'Horse Brilliant' shape definition for grading Horse Head diamonds. While there are many examples of poorly cut Horse Heads that only superficially resemble a horse, a well-cut stone is unmistakable. Some more adventurous cutters even claim to be able to create stones that distinguish between a mare and a stallion.
Color is probably one of the most elusive and captivating characteristics of a diamond. Color is graded from D to Z – from colorless to brown or light yellow. The closer a diamond's color is to D, the more colorless it is and the higher its value. Diamonds of different colors will differ dramatically in value.