Of the 4Cs, cut is the most important characteristic of a diamond and it has the greatest overall impact on a diamond’s beauty. Diamonds have the unique ability to manipulate light (aka fire, sparkle, and brilliance) that can only be realized with an extremely high level of accuracy during the cutting and polishing process. Nature dictates color and clarity, but humans affect the cut. When cutting diamond rough, the cutter not only considers the proportions of a diamond, but the craftsmanship of overall symmetry and polish as well. Light enters and exits though the crown reflecting from one facet to another. A diamond that is cut too shallow or too deep will not reflect light properly and the diamond will not be as brilliant as a diamond with an excellent cut grade.
Diamond’s Light Return
In early 2005, GIA (Gemological Institute of America) introduced a diamond cut grading system for round brilliant cut diamonds in the D-Z color range and flawless to I3 clarity range. In January 2006, these new cut grades ranging from excellent to poor were added to all GIA diamond certificates (aka diamond plot). To achieve the cut grading system, GIA calculated the cut results for 38.5 million cut proportion sets based on the evaluation of seven components. The first three were related to appearance and brightness and the last four were related to overall craftsmanship.
GIA Cut Grades
Excellent
Very Good
Good
Fair
Poor
When purchasing a diamond, we recommend purchasing the best possible cut grade within your budget. Unlike color and clarity; which are personal preferences, cut is extremely important.
Visit our education section for more on diamond cut.