As we all known, diamond’4C is Cut, Clarity, Color, and Carat, the cut of diamond is the only important factor affected by human being, who affects the fire and brilliance of diamond, so the cut is an important indicator for measure whether the diamond is luminous, diamond cut also has its hierarchy standard. GIA （Gemological Institute of America） is the most authoritative diamond grading certificate in the world, from GIA’s diamond cut grading system, the grade from high to low is excellent, very good, good, fair and poor. Diamond cut is the proportion designed by a technician, the ratio of pavilion angle and crown angle effects diamond’s cut grade; the great proportion can make diamond looks more brilliant.
Poor cut: which includes all the diamonds that not meet cut standard, these diamond’s cut whether shallow and wide or deep and narrow and result in the light escape from the side or bottom of diamond easily.
Fair cut: about 35 percent diamond belongs to this cut grade, even though the fair cut is better than poor cut, but the light reflected is less than good cut.
Good cut: This is a kind of high-quality diamond cut, about 25 percent diamond belongs to good cut grade, which can reflect most of the light successfully.
Very good cut: about 15 percent diamond belongs to very good cut grade, the fire and brilliant is nearly equal to excellent cut diamond, but the price is lower than excellent cut.
Excellent cut: this is the best cut grade of diamond, only about 3 percent diamond belongs to this cut grade, which can reflect almost all the light, so the diamond has the most beautiful light.