In the 1940s and 50s, the Gemological Institute of America (GIA) developed an international grading system based on the 4 Cs: Carat, Color, Clarity, and Cut. These 4 characteristics taken in combination determine the value of a diamond.

Carat is perhaps the most obvious value factor when it comes to diamond shopping. The bigger the diamond, the more it’s going to cost, right? The carat is the unit of weight for gemstones, and is usually rounded to the hundredth. Most of the diamonds used in jewelry weigh one carat or less. So here’s an inside tip on diamond shopping: think about purchasing a diamond that is slightly smaller than a full or half carat size. The price of a diamond increases greatly when they weigh in at these sizes so by looking at a diamond just slightly smaller than an even weight you’ll save a nice chunk of change without sacrificing anything in looks.

Color.  The closer to colorless a diamond is, the more rare and valuable it is. Most diamonds have slight amounts of yellow or brown in their color. Most diamonds are graded on a scale developed by GIA and assigned a letter D-Z (the letters A-C are no longer used to avoid confusion or association with older grading systems).  The letter D represents a perfectly colorless diamond and each subsequent letter represents a specific range of color, ending with Z a near colorless diamond.

Clarity refers to the absence or presence of any inclusions or blemishes that were formed as the diamond itself was born- a sort of fingerprint that is unique to each diamond. Clarity is also graded on a scale, with diamonds falling anywhere in a range from Flawless to Included, dependant on how visible any inclusions are. This is the scale:

• Flawless (FL) – No inclusions or blemishes are visible to a skilled grader using 10× magnification
• Internally Flawless (IF) – No inclusions and only blemishes are visible to a skilled grader using 10× magnification
• Very, Very Slightly Included (VVS1 and VVS2) – Inclusions are difficult for a skilled grader to see under 10× magnification
• Very Slightly Included (VS1 and VS2) – Inclusions are clearly visible under 10× magnification but can be characterized as minor
• Slightly Included (SI1 and SI2) – Inclusions are noticeable to a skilled grader using 10× magnification
• Included (I1, I2, and I3) – Inclusions are obvious under 10× magnification and may affect transparency and brilliance

Cut. The most common cut for diamonds is the round brilliant, but there are many other fancy cuts that are also used: marquise, pear, oval, emerald cut, etc. The cut of a diamond affects its brilliance, fire, and sparkle. When grading a diamond’s cut, professionals look at the proportions, symmetry and the polish of the diamond.

Anytime you’re interested in a diamond for purchase, take into consideration these 4 value factors while making your decision. Jewelers should always provide you with the grades of the diamond, whether it’s set in a piece of jewelry or sold loose.