Know the Four Cs:
Refers to the diamond’s shape, quality, proportions, symmetry and polish. Some of the most common shapes are round, princess, marquise, pear, heart, oval, emerald, cushion, radiant and Asscher (square emerald cut). According to Josh Holland of Blue Nile Jewelry, a diamond’s cut is the most important factor. “A well-cut diamond will sparkle more, making the stone appear bigger,” he says.
A diamond’s weight is measured in carats, which are subdivided into 100 equal parts called points. One point equals .01 carat or 1/100 carat.
diamonds are the most desirable since they allow the most refraction of light (sparkle).
Gemolo-gists use a grading scale set forth by the Gemological Institute of America (GIA) to determine a diamond’s clarity, which is how clean the gem appears when viewed through a 10x magnifier.