Cut Grading Across Diamond Shapes
Cut grading only tends to be provided for Round diamonds. This is because it is extremely difficult to assess the ideal proportions of the likes of Marquise and Cushion. However, there are some experts that have done research about the ideal proportions for these shapes, and thus we will provide you with a small guide below.
In short: GIA assigns formal cut grades (Excellent → Poor) only to round brilliants — fancy shapes (oval, princess, emerald, cushion, marquise, pear, heart, radiant, Asscher) carry no official cut grade because optimal proportions vary by silhouette. Judge fancy cuts by length-to-width ratio, light-return symmetry, bow-tie severity in elongated cuts, and table-to-girdle alignment. Polish and symmetry grades still appear on every certificate.
Step Cuts
(Asscher and Emerald)
Excellent
Depth percentage – 58 - 65
Table percentage – 60 - 65
Very good
Depth percentage – 55 – 70
Table percentage – 59 - 70
Good
Depth percentage – 52 - 75
Table percentage – 52 - 75
Excellent
Depth percentage – 58 - 65
Table percentage – 60 - 65
Very good
Depth percentage – 55 - 70
Table percentage – 59 - 70
Good
Depth percentage – 52 - 75
Table percentage – 56 - 75
Modified Brilliant Cut Diamonds
(Pear, Princess, Marquise, Radiant, Oval, and Heart)
Here is a guide to the depth percentage and table percentage you should be looking for in regards to each of the sought after grades.
Excellent
Depth percentage – 58 - 64
Table percentage 55 - 62
Very good
Depth percentage – 57 - 66
Table percentage – 53 - 64
Good
Depth percentage – 56 - 68
Table percentage – 52 - 65
Excellent
Depth percentage – 62 - 73
Table percentage - 57 – 72
Very good
Depth percentage – 60 - 77
Table percentage – 55 - 75
Good
Depth percentage – 57 - 83
Table percentage – 52 - 85
Excellent
Depth percentage – 58 - 64
Table percentage – 55 - 62
Very good
Depth percentage – 57 - 66
Table percentage – 53 - 64
Good
Depth percentage – 56 - 68
Table percentage – 52 - 65
Excellent
Depth percentage – 52 - 60
Table percentage – 55 - 62
Very good
Depth percentage – 50 - 62
Table percentage – 50 - 62
Good
Depth percentage – 45 - 65
Table percentage – 52 – 65
Excellent
Depth percentage – 58 - 64
Table percentage – 55 - 62
Very good
Depth percentage – 57 - 66
Table percentage – 53 - 64
Good
Depth percentage – 56 - 68
Table percentage – 52 - 65
Excellent
Depth percentage – 62 - 68
Table percentage – 58 - 65
Very good
Depth percentage – 58 - 70
Table percentage – 56 - 70
Good
Depth percentage – 57 - 75
Table percentage – 54 -75
Round Brilliant Cut
This is the most brilliant of all the diamond cuts. Here is a guide to the depth percentage and table percentage you should be looking for in regards to each of the sought after grades.
Excellent
Depth percentage – 60 - 63
Table percentage – 53 – 58
Very good
Depth percentage – 58 - 64
Table percentage – 52 - 62
Good
Depth percentage – 56 - 67
Table percentage – 50 - 67
Types of diamond cuts: frequently asked questions
What's the difference between a cut and a shape?
Shape is the outline you see from above. Cut refers to the faceting style and how well it's executed. A pear shape, for example, is cut in the brilliant style.
Which diamond cut sparkles the most?
Brilliant cuts sparkle most. The round brilliant leads the field with 57–58 facets arranged to fire light straight back at you.
What is a step cut?
Step cuts, such as emerald and Asscher, use long, straight facets that run parallel to the girdle. They trade flashy sparkle for clean lines and a glassy, hall-of-mirrors look.
What is a mixed cut?
A mixed cut blends both styles — often a brilliant-cut crown with a step-cut pavilion. The radiant is the best-known example, pairing sparkle with a crisp outline.
