The 4Cs
The 4Cs are a set of criteria established by the Gemological Institute of America (GIA) for evaluating the quality of diamonds. They stand for Carat weight, Cut, Colour, and Clarity
4Cs-CUT
Cut is one of the most important factors of the 4Cs and draws attention to the diamond’s beauty and brilliance. A diamond’s cut will affect how it handles light as it reflects and refracts to the eye. Many people confuse diamond shape with diamond cut. Although related, they are quite different. Shape describes the basic outline of the diamond. Some popular diamond shapes include round, emerald and oval. Cut or cutting style, on the other hand, refers to how a diamond’s facets are arranged. For example, most diamonds are brilliant cut. The quality of a diamond’s cut is based on its symmetry, polish and overall quality of craftsmanship.
4Cs-CARAT
Carat is a unit of weight that equals 0.2 grams. That means a 5 carat diamond weighs 1 gram. Carat weight relates to the size of a diamond, which is one of the most visible things about a stone. How large a stone looks, though, also depends on how it is cut. Stones that are cut too deep may weigh more, but they will not look any bigger face-up. That is one of the reasons why it is important to buy a stone that is well cut.
4Cs-COLOUR
What many people call “white diamonds” are actually colourless diamonds. These diamonds are graded on GIA’s D-Z colour grading scale, with D being completely colourless. The more colourless a diamond is, the rarer and more valuable it is. D-F diamonds are considered colourless while G-J diamonds are near-colourless. If you are looking for a diamond that doesn’t have noticeable colour that is cost effective, consider diamonds in the near- colourless range.
4Cs-CLARITY
Diamonds almost always contain inclusions, such as tiny crystals or feathers, and blemishes, such as nicks or scratches. Clarity considers the number, size, location, color or relief and type of these inclusions and blemishes (called clarity characteristics). The less noticeable they are, the rarer and more valuable the diamond is, if everything else is the same. Diamonds that are Flawless have no visible inclusions or blemishes at 10 × magnification.
Diamonds can contain external or internal imperfections known as blemishes and inclusions. Clarity is evaluated on the degree of which these imperfections are visible. Diamond imperfections are often difficult to see with the naked eye, however significant imperfections may affect brilliance.
Additional GIA Grading Information
POLISH
The level of smoothness from surface defects created from polishing. Excellent to good grades or not visible to the naked eye. Only severe defects may affect light patterns as light rays enter and exit the diamond.
SYMMETRY
The alignment and intersections of the facets on the diamond. Symmetry can affect the diamond’s brilliance as it may redirect light rays.
FLUORESCENCE
Fluorescence is the glow you sometimes see when an object emits visible light. Some diamonds fluoresce when they are exposed to long-wave ultraviolet (UV) rays from sources like the sun. This can cause them to emit a bluish light or more rarely, a yellow or orangy light. Once the UV light source is removed, the diamond stops fluorescing. The presence of fluorescence will not affect the colour in a major way as other factors.
