Girdle is the edge of a diamond, the widest part of any diamond. It is formed while edging or cutting a diamond and is important for diamond cutters. Since the girdle is the widest part of any diamond, the width of any diamond is measured by measuring its girdle. It is measured lengthwise as 100%. A girdle can be a guideline towards the excellence of a cut and, therefore, the quality of any diamond. Most diamonds have two divisions - crown and pavilion, and the girdle is the meeting point or joint of these two limbs of a diamond.
Three main types of girdles are faceted, bruited, and polished. A faceted girdle means rows or waves of small polished sides around the diamond. A brutes diamond girdle means just one row of the unpolished exterior. A polished girdle is a smooth one, as obvious from its name. Interestingly, unlike cut, color, clarity, and carat, these types of girdles in a diamond do not directly influence its value.
GIA has laid down the following scales of a girdle:
-Extremely Thin
-Very Thin
-Thin
-Slightly Thin
-Medium
-Slightly Thick
-Thick
-Very Thick
-Extremely thick