Carat – How Much It Weighs
Diamonds are sold by the carat (ct), which is a unit of weight, not
size. One carat weighs 200 milligrams, the world standard since
1914. A carat is divided into 100 points, with one point
corresponding to .01 carat.
Clarity – How Pure It Is
Clarity refers to a gemstone’s purity. Virtually all diamonds contain
tiny natural birthmarks that are present to varying degrees. These
marks serve as the identifying fingerprint that makes every
gemstone unique. Clarity is evaluated by viewing the gemstone under 10X magnification. Clarity grades range from FL (flawless) to I3 (contains obvious inclusions visible to the naked eye).
Color – How Colorless It Is
Color refers to the color within the diamond, not the color of the
reflected light. The absence of color makes one diamond more
precious than another. The whiter or more colorless the gemstone, the more rare it is, and higher the price it will have. Color is graded with letters ranging from D, which is completely absent of color, to Z, which is light yellow.
Cut – How Much It Sparkles
Cut has the greatest single influence on a diamond’s sparkle. Of
the four qualities that define a diamond's value, the cut is the only
one determined by a human being. A skilled diamond cutter
realizes the rough diamond's potential.
They cut and facet the crystal to reflect the maximum amount of light inside the gemstone and back through the top of the diamond. Diamonds can be cut too shallow or too deep, both of which cause light to leak out of the bottom and sides of the stone, diminishing its sparkle.