GIA Classifications

CLASS I American/Tolkowsky Cut

Table: 53-60% of diameter of stone for round, marquise, pear and oval; 58-64% of diameter of stone for emerald and rectangular

Total depth: 59.3-61% of diameter of stone for round, marquise, pear and oval; 58-64% of diameter of stone for emerald and rectangular

Crown angle: 34-35 degrees for round, marquise, pear and oval 33-35 degrees for emerald and rectangular

Crown height: 13.5-16.2% of diameter of stone for round, marquise, pear and oval and 11.7-16.2% of diameter of stone for emerald and rectangular

Girdle thickness: .7-1.7% of diameter of stone (medium)

Pavilion angle: 40.20 to 41.20 degrees for rounds; 39.25 to 40.75 degrees for marquise, pear and oval; 43.8 to 46.8 degrees for emerald and rectangular

Pavilion depth: 42.52-43.57% of diameter of stone for round, marquise, pear and oval; 47.6-53.1% of diameter of stone for emerald and rectangular

CLASS II

Table: 53-64% for round, pear, marquise and oval; 53-65% for emerald and rectangular

Total depth: 56-61% for round, marquise, pear and oval; 56-65% for emerald and rectangular

Crown angles: 32-35 degrees for all shapes

Crown height: 11.2-16.2% for all shapes

Girdle thickness: Thin to thick for all shapes (medium preferred)

Pavilion angle: 40 to 41.5 degrees for rounds; 39.25 to 40.75 degrees for pear, marquise and oval; 43.3 to 46.8 for emerald and rectangular

Pavillion depth: 42.31-43.89% for rounds; 41.51-43.1% for pear, marquise and oval; 47.1-53.1% for emerald and rectangular

Polish & symmetry: Good

CLASS III

Table %: 65-70% for round, marquise, pear and oval; 66-70% for emerald and rectangular

Crown angles: 30-32 degrees for all shapes

Girdle thickness: Very thin or very thick for all shapes

Pavilion angle: Any measurement other than 40 to 41.5 degrees for rounds or 39.25 to 40.75 degrees for marquise, pear and oval; any measurement other than 43.3 to 46.8 degrees

Polish & symmetry: Fair to good

CLASS IV (50-60% below cost)

Table %: 70% and above for all shapes

Crown angles: 30 degrees and below for all shapes

Girdle thickness: Extremely thin to very thin or very thick to extremely thick for all shapes

Pavilion angle: Any measurement other than 40 to 41.5 degrees for rounds or 39.25 to 40.75 degrees for marquise, pear and oval; any measurement other than 43.3 to 46.8 degrees

Polish & symmetry: Fair to poor

by Fred Cuellar, author of the best-selling book “How to Buy a Diamond.” More questions? Ask the Diamond Guy
The founder and president of Diamond Cutters International, is one of the worlds top diamond experts, as well as a three-time Guinness Book record holder in jewelry design.
Fred Cuellar
Latest posts by Fred Cuellar (see all)

This website uses cookies to improve your experience. We'll assume you're ok with this, but you can opt-out if you wish.

A few steps for you to expect once you submit your form - We will first send you an email confirming that we’ve received your form, so keep an eye out for that.  We will then contact you within 24 hours via your preferred method of contact. We will work with you to setup a complimentary one-on-one consultation with your gemologist.