Understanding the Major Determinants of Diamond Value

Not all diamonds are created equal, and the Gemological Institute of America (GIA) found a way to explain why.

In the 1950s, the GIA proposed a grading system to evaluate a diamond’s worth based on the 4 Cs: Cut, Colour, Clarity, and Carat Weight. It has been widely accepted and used by diamond professionals ever since; visit a diamond seller today, and you’ll definitely be looking at these scales.

In this article, we will explore and explain the 4 Cs to help you navigate your diamond buying or selling process.

The 4 Cs 

The 4 Cs determine a diamond’s appearance, quality, and value. Diamonds are graded consistently based on these characteristics before being priced by diamond sellers.


The cut of a diamond refers not exactly to its shape but how well it interacts with light. It is generally considered the most important aspect of a diamond’s quality, impacting its brilliance and, therefore, its desirability to buyers.

Generally, the higher the diamond’s cut grade, the brighter it is. When a diamond is well-cut, light enters and exits the diamond through the same surface, causing it to appear bright, colourful, and scintillating. In a poorly cut diamond, the light may enter its crown and exit through the pavilion, resulting in a dark and unattractive look.


The clearer the diamond, the higher its value.

According to the GIA, diamonds range from D to Z, with D being the most colourless, and Z containing visible yellow or brown tints. The closer it is to being colourless, the rarer and more valuable it becomes.

Gemologists also consider fluorescence, or whether a diamond emits visible light under ultraviolet light. A strong blue fluorescence diamonds of I – M colour grades appear up to one grade lighter.


Most diamonds have internal features (inclusions) and surface irregularities (blemishes). The former generally exist on the inside of a diamond, while the latter include scratches on its surface.

Diamonds with fewer inclusions and blemishes are more highly valued.

The size, location, and darkness of these clarity characteristics also matter. If a diamond’s inclusions or blemishes interfere with the light as it passes through the gem, its brilliance and beauty will be dulled, thus resulting in a lower price.

Carat Weight 

Carat weight refers not to how large the diamond is, but the weight of it, with a 1-carat diamond being 0.2 grams.

Moreover, large diamonds are rarer than small diamonds and are thus of higher value, costing more per carat. Therefore, a one-carat diamond is worth more than the sum of four 0.25-carat diamonds.


Before you go ahead and sell your diamond, it is critical to develop a deep understanding of the 4 Cs, which dictate how much you should be getting in return. In general, cut is the top priority characteristic, followed by colour, clarity, and carat weight.

Check us out at Jumbo Gold and Diamonds, one of Singapore’s leading gold and diamond traders. We buy and sell gold and diamond jewelry, silver and gold bullion, and more. We also provide no-obligation appraisals. Reach out to us for more information.