IDGL Diamond and gem grading

Grading Diamonds

We use the internationally recognized GIA colour grading system. Below is a sample form we use to grade your items.

Colour grading

To grade clarity, that is the visual appeal and condition of the diamond, we use the following clarity chart. It covers eleven major clarity grades.

Grading

The overall evaluation of the cut grades and appearance of a diamond is based on a cross section of observed characteristics. Some diamonds, especially old cuts, are cut for maximum weight retention from their original rough crystals at the expense of the cut qualities. That explains why old cut diamonds look dull in comparison to modern brilliant cuts. Some are cut too shallow to avoid, for example, unsightly inclusions. These deviations from the ideal proportions of a modern faceted diamond result in loss of fire and brilliance.
Diamond has the highest refractive index (2.42) of all known gemstones and the way it is cut has an overall effect on its appearance in terms of fire and brilliance.
In stones cut too shallow, light escapes out of the pavilion facets instead of reflecting off the table and crown facets on the top.
Light is poorly reflected in deeply cut stones which give a dark appearance.
In an excellent cut diamond, the internally refracted rays of light bounce off the pavilion facets below and through the table and crown facets above, resulting in maximum fire and brilliance. The following diagram illustrates key aspects of an ideal cut diamound.

Grading

 


 

"Praise, like gold and diamonds, owes its value only to its scarcity."
: Samuel Johnson

Diamond Grading
Sorting out the clients items to be tested, graded and certified.

Grading Certificates For
Items of All Value

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Call us now on
0113 224 2498

IDGL Chief Gemologist Mr. S. Chung F.G.A. Recipient, G.I.A. Diamonds and Diamond Grading Certificate.