How Fancy Cut Diamonds are Graded – GemSelect AU
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How Fancy Cut Diamonds are Graded

Posted by MICHAEL Hart on

The Round Brilliant is by far the most popular diamond cut on the market. But with so much focus on the round Brilliant, it’s easy to forget about the wide variety Fancy cuts that are available. This post introduces the reader to the world of Fancy Cut Diamonds and how industry professionals grade them.

 There are three major cutting styles that most diamonds fit into: Brilliant Cut, Step Cut and Mixed Cut. Many Fancy cut Diamonds are variations of the Round Brilliant. Oval Cuts, Marquise, Hearts, Pears, Trillions and Cushions evolved from the round Brilliant. All Fancy Cut Diamonds have variables by which they are graded, but unlike Round Brilliants, grading Fancy cuts is a matter of personal preference.

 Clarity

Clarity is important in Fancy Cut diamonds because many Fancy Cut stones have large tables that make inclusions easy to see. Graders consider the size of the inclusion(s), location, number relief and nature. Clarity Grading is the same for round Brilliants and Fancy Cuts.

 Color

Fancy Cut Diamonds tend to show more color than Round Brilliants at the end of the D-Z color range. Because of this, Fancy cuts with a color grade of Q or lower are also viewed face-up to confirm if they have enough color to be graded on the Colored Diamond scale

 Table Crown and Girdle

The tables of Fancy cuts are generally larger than Round Brilliants. To calculate the table percentage of Fancy Cuts, graders measure the table size and divide by the stone width and multiply by 100 (Table size/stone width X 100 = Table %) The Crown angle is estimated by looking lengthwise at the stones profile and assigning a descriptive term. Terms can include Acceptable, Shallow, Very Shallow, Slightly Steep and Very Steep. Girdle thickness percentage is calculated the same as Round Brilliants.

 Pavilion Depth

Graders check the Pavilion Depth by looking at the stones profile and comparing the crown height to the pavilion Depth. To be well proportioned a gem’s pavilion should be 2.5 to 4.5 times the size of its crown. Similar to the Crown Angle, the Pavilion can receive a grade of Acceptable, Shallow, Very Shallow, Slightly deep and Very deep.

 Shape appeal

Graders judge Symmetry and Shape appeal differently. With Symmetry, each Diamond is considered individually. With appeal, the Diamonds appearance is assessed in relation to other Diamonds of the same style. The trade considers certain proportions to be attractive, and diamond within this range will always sell faster then diamonds that are radically different.

 Finish

As with Round Brilliants, a Fancy Cut Diamond’s finish is made up of Polish and Symmetry. Polish can be rated Excellent, Very Good, Good or Poor. Symmetry involves analysing each part of the diamond separately and then comparing those parts as a whole.


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