Crown facets should be exactly above the pavilion facets. For diamonds up to 0.99 ct. in weight (except for Emerald, Baguette, and Square shapes), twisting of the crown edges relative to pavilion edges is tolerated within

• - 10% of the base of the upper girdle facet for A-group diamonds,
• - 20% of the base of the upper girdle facet for B-group diamonds.

All the cutting elements of the crown of a diamond 1.00 ct. and more in weight should be visually symmetrical to those of the pavilion.

Curved facets and edges and chips visible at tenfold magnification are not tolerable.

The facet surfaces should be carefully polished. The surfaces must not show any traces of graphitization, lines, scratches, and other fashioning defects visivle at tenfold magnification.

If a diamond contains internal natural defects (twinning lines, inclusions, cracks), their traces may be present in any part of the surface as points or lines, provided the boundaries of the defects are not chipped off.

The pavilion stages of diamond shapes Emerald, Square, and Baguette should decrease in height from the girdle to the culet, and the crown stages should decrease in height from the girdle to the table.

The facets of one stage should have the same height.

The height of the second or the third stage of the crown should be equal to a half of the height of the previous lower stage.

The height of the second stage of the pavilion should be 80-90% of that of the first stage, and the height of the third stage should be 20-25% of that of the second stage.

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The height of the upper girdle facets, when measured in plan, should account for 40-50% of the crown height. The height of the lower girdle facets should account for 75-90% of the pavilion depth. This parameter should be kept the same for a particular diamond.

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The pavilion surface of Marquise, Pear, and Oval diamonds up to 0.29 ct. in weight may have no more than four naturals and extra facets, while diamonds 0.30 ct. and more in weight may have no more than two naturals or one natural and one extra facet. The naturals may have the morphological features inherited from the original diamond crystal without significant step structure and etch figures. Extra facets and naturals should not affect the face-up outline of the girdle and should be invisible through the table in the direction parallel to the symmetry axis of a diamond.

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The size of the culet should be no more than 2% of the stone width for diamonds up to 0.49 ct. and no more than 1% of the stone width for diamonds more than 0.50 ct. Diamonds weighing 1.00 ct. and more may have a culet which is seen as a point at tenfold magnification. The shift of the culet and table center from the symmetry axis is tolerable within 2% of the stone width for diamonds up to 0.29 ct. in weight and within 1.5% of the stone width for diamonds from 0.30 to 0.99 ct. in weight. For diamonds more than 1.00 ct. in weight, the tolerance for culet shift is established at 0.5% of the stone width.

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The girdle of a diamond should be regular in shape, and its thickness would be kept within specified limits.

The surface of the girdle should be clean, even, and mat-gray. Abrasion of the girdle surface should be minimum and correspond to that of a masterstone. The girdle thickness in the places where naturals are left should be at least 50% of the girdle thickness above the adjacent facets (upper or lower girdle facets).

Diamonds of Emerald, Baguette, and Square shapes must have a polished girdle. When the girdle is polished, its shape and thickness should be kept within the specified limits established for Pear and Marquise shapes.

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Cutting shapes	Weight
	less than 0.29 ct	0.30 ct
Marquise, Pear, Oval	No limitations
Emerald, Princess, Baguette, Square	Up to 4 grade	Up to 6 grade

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Emerald cut	At least 0.10 ct
Baguette	From 0.05 to 0.50 ct
Square	From 0.05 to 0.29 ct
Marquise	No limitations
Pear	No limitations
Oval	No limitations
Princess	At least 0.05 ct

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Marquise	Stones up to 0.29 ct in weight may have clarity up to Grade 5, Stones 0.30 ct in weight and more may have clarity up to Grade 8
Pear
Oval
Emerald	Stones up to 0.29 ct in weight may have clarity up to Grade 5 Stones 0.30 ct in weight and more may have clarity up to Grade 7
Square
Baguette
Princess

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Cutting style	Deviation
Marquise	1.5 % of stone width
Pear
Oval

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Cutting style	Weight, ct	Microcracks are not tolerated
		Clarity grade	Color grade
Marquise	Up to 0.29	1-3	1-3
Pear	Up to 0.30	1-4	1-6
Oval	Up to 0.50	1-7	1-6

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