Diamond Cut - GIA

Download our Diamond Grading Sheet file (pdf format)

GIA Cut Grade

The GIA cut grade is assigned as:

• Excellent
• Very Good
• Good
• Fair
• Poor

Seven factors are considered to produce this cut grade:

• Brightness
• Fire
• Scintillation
• Weight Ratio
• Durability
• Polish
• Symmetry

Face-up Appearance Factors

Brightness: the total of all internal and external reflections of white light.

Fire: the angled facets of a diamond work together to break white light into the spectral colors. 

Scintillation: the combined effect of the sparkle and pattern of a diamond. 

Design Factors

Weight Ratio: the comparison of a diamond's weight to it's diameter. A diamond should be neither too heavy nor too light for the diameter.

Durability: the potential risk for damage due to overly thin girdles or points.

Craftsmanship Factors

Polish: the extent to which facets are finished without visible signs of cutting and polishing.

Symmetry: the exactness of the diamond's shape based on even proportions, and facet placement.

Through extensive research the GIA has evaluated the result on the appearance of a diamond based on the many different variations of diamond proportions. The following measurements are all considered to produce a resulting grade: table size, crown angle, pavilion angle, culet size, star facet length, lower half facet length, girdle thickness percentage, crown height and total depth.