Terms I-R

Jewelry Guide: Glossary Terms: I-R

Illusion setting

This setting is more intricate than others in that it surrounds the stone to make it appear larger. The metal that surrounds the stone usually has an interesting design.


Often referred to as “nature’s fingerprints,” these are internal imperfections within most diamonds. They are what makes a diamond so unique, as a fingerprint does for a person. These birthmarks are measured on a scale of perfection known as clarity. Some common names of inclusions include cloud, crystal, pinpoint, and feather. The position of inclusions can affect the clarity of a diamond and therefore the value.Click here for more on clarity.

Marquise shape

A boat-shaped diamond that is long and thin with gently curved sides that come to a point on either end. Marquise is part of the brilliant-cut family.


This cut has both step-cut and brilliant-cut facets. Mixed cuts combine the beauty of the emerald cut with the sparkle of the brilliant cut.


Bottom portion of the stone, under the girdle, measuring to the culet.


A pinpoint is a small dot, which is an inclusion within a diamond. A gathering of pinpoints is called a “cluster” or “cloud.” A cloud or cluster can appear as a hazy area in the diamond.


Indicates the care taken by the cutter in shaping and facetting the rough stone into a finished and polished diamond.

Poor cut

Cut refers to the angles and proportions a skilled craftsman creates in transforming a rough diamond into a finished diamond. A poorly cut diamond can be either cut too deep or too shallow. A deep or shallow cut diamond will lose or leak light through the side or bottom. This results in less brilliance and value. Click here to learn more about cut.

Princess cut

A square or sometimes rectangular-shaped modified brilliant-cut diamond.

Prong or claw setting

It consists of four or six claws that cradle the diamond. Because this setting allows the maximum amount of light to enter a stone from all angles, it sometimes can make a diamond appear larger and more brilliant than its actual weight. This setting can also hold larger diamonds more securely.


The proportions of a diamond are very important, so that the maximum amount of light be reflected off and out of a stone. Proportion is the relationship between the angles of the facets of the crown and pavillion.

Radiant cut

A rectangular or square shaped diamond with step-cut and scissor-cut on the crown and a brilliant-cut on the pavilion.