Organisation of diamond industry members. The main purpose of a diamond bourse is to provide an environment for the trading of diamonds within a set of ethical business practices. All diamond bourses have a legal, ethical framework to enact regulations for members and protect consumer confidence. Also referred to as a ‘Diamond Club’.
Cut-for-Weight
A diamond that is fashioned so as to minimise the amount of rough diamond crystal cut away. Carat weight may be gained, but brilliance, fire, and beauty are lost. The resulting proportions can make some diamonds look ‘bulgy,’ ‘lumpy’, ‘deep,’ or ‘undersize,’ while others may be flat or have symmetry deviations.
Depth
Cushion Cut
Diamond cut or shaped into a squarish or rectangular outline, with rounded corners. A brilliant cut cushion is one of the diamond shapes that can display hearts & arrows.
Cut
Can refer to any or all of the following: proportions, polish, symmetry, and/or shape and style of cutting (brilliant cut or step cut). The overall cut grade is one of the four c’s of diamond grading that determines the overall diamond quality and value.
Cut Grade
Qualitative description of the overall make of the diamond, taking into consideration the proportions, polish, and symmetry. Cut is one of the four c’s of diamond grading that determines the overall diamond quality and value.
Cubic Zirconia
Colourless, transparent, man-made material that is often used to imitate diamond – a diamond simulant. The chemical name is zirconium dioxide (ZrO2).
Culet
Tiny point on the bottom of a brilliant cut diamond, or the bottom edge of a step cut diamond. A culet can be prone to damage, thus diamonds are usually set in jewellery in such a way that the culet is protected.
Crown Height Percentage
Crown Height expressed as a percentage of the diameter.
Crystal
Type of inclusion where a mineral deposit, or sometimes another diamond, is trapped inside the diamond. Crystals often look like bubbles of various shapes and sizes.