One carat equals 1/5 of a gram in weight
For diamonds under a carat, each carat is divided into 100 points – similar to pennies in a dollar. 0.75ct. = 75 points, ½ ct. = 50 points
The GIA Clarity Scale includes eleven clarity grades ranging from Flawless to I3. Given that diamonds form under tremendous heat and pressure, internal and external characteristics are common. These characteristics help gemologists separate natural diamonds from synthetics and simulants, and identify individual stones.
There are two types of clarity characteristics: inclusions and blemishes – the difference is based on their locations. Inclusions are enclosed within a diamond while blemishes are confined to its surface.
The GIA Color Scale extends from D (colorless) to Z (light yellow or brown). Although many people think of gem quality diamonds as colorless, most diamonds used in jewelry are nearly colorless with tints of yellow or brown. Color grades are determined by comparing each diamond to a master set. Each letter grade represents a range of color and is a measure of how noticeable the color is.
The GIA Cut Scale ranges from Excellent to Poor. GIA provides a cut quality grade for standard round brilliant diamonds that fall in the GIA D-to-Z color range.