Cushion Cut Diamond: Shape, Grades and SA Value Guide

What defines a cushion cut

A cushion cut diamond has a square or rectangular outline with rounded corners, resembling a cushion or pillow. The facet arrangement can follow either a classic crushed-ice pattern, where light breaks into many small reflections, or a chunky or modified brilliant pattern, where larger facets create a more distinct pattern. Neither is objectively better, but they produce different visual effects that buyers either prefer or dislike.

How cushion cuts are graded

GIA grades cushion cut diamonds as Excellent, Very Good, Good, Fair, or Poor for overall cut only for rounds. Cushion cuts receive grades for polish and symmetry but not an overall cut grade the way round brilliants do. This means proportions and appearance must be assessed from the measurements and an actual viewing, not from a single grade line on the certificate.

Cushion vs round brilliant in SA pricing

Cushion cuts typically cost less per carat than round brilliants of equivalent colour and clarity because they retain more rough diamond during cutting and face up slightly smaller. A buyer who prefers the cushion shape can often get a larger-looking stone for less than an equivalent round. The trade-off is that cushion cuts show colour more than rounds, so buyers sometimes need to choose a higher colour grade.

Buying advice for cushion cuts

Ask for millimetre measurements and the length-to-width ratio. For a square look, target a ratio near 1.00 to 1.05. For a rectangular cushion, look at 1.10 to 1.20 or beyond. Request a video of the stone in multiple lighting conditions because crushed-ice and chunky patterns look very different in still photographs. Prodiam in Bedfordview can source and assess certified cushion cut diamonds. Contact sales@prodiam.co.za or call +27 11 334 9010.

Decision table

Use the details, not a shortcut.

Attribute	Square cushion	Rectangular cushion
Length-to-width ratio	1.00 to 1.05	1.10 and above
Face-up appearance	Balanced, equal sides	Elongated, finger-slimming
Pattern type	Crushed-ice or chunky	Crushed-ice or chunky
Colour visibility	More than rounds	More than rounds
Common settings	Halo, solitaire, pave band	Halo, three-stone, solitaire

Direct answers

Common questions

Is a cushion cut cheaper than a round brilliant?

Generally yes. Cushion cuts typically cost less per carat than rounds of comparable grades because round cutting wastes more rough diamond and commands a market premium.

Does a cushion cut show colour more than a round?

Yes. The larger facets in cushion cuts tend to show warmth more than round brilliants. Buyers often move one colour grade higher when switching from round to cushion.

What is the difference between cushion modified brilliant and cushion brilliant?

The difference lies in the facet arrangement. Cushion modified brilliant typically produces a crushed-ice effect. Standard cushion brilliant produces larger, more defined facets. Both are cushion cuts by outline.

What length-to-width ratio is most popular?

Square cushion cuts near 1.00 to 1.05 are the most popular for engagement rings in current South African retail. Preference varies and neither ratio is universally better.

Can I see a cushion cut diamond before buying?

Prodiam can arrange viewings of certified natural diamonds in Bedfordview, Johannesburg. Contact the team to discuss what is available and set up an appointment.

Cushion cut diamonds: what the shape means and what to look for.