How to Choose a Diamond

The Four C's of Diamonds


All diamonds contain minute inclusions or blemishes determining their clarity. Most inclusions cannot be seen by the untrained naked eye, and only someone with a trained eye using a 10X microscope can locate them. The fewer the inclusions the higher the clarity, and rarer the stone.

Diamond clarity chart


A diamond's colour can range from colourless to shades of yellow or brown. Colour is an important factor in determining a diamond's value. The closer a diamond is to colourless the more rare and expensive the diamond is. Letters of the alphabet are used to help place diamonds into their appropriate colour category. This is called "colour grading" and is provided by the Gemological Institue of America (GIA). It is a system that is used world wide.

Gemological Institute of America Colour Grading Scale
colourless nearly
very light yellow light yellow to
strong yellow

Carat Weight

The most obvious "C" to an untrained eye is carat weight. Diamonds are measured by their weight in carats (1 carat = 200 milligrams). Stones are measured to the nearest hundredth of a carat. A hundredth of a carat is also called a point. Thus, a 0.50 carat diamond can also be described as a half-carat or 50 point diamond. A one carat round diamond can have different diameters depending on the proportions of how diamond is cut. The illustration below shows the relative diameters of different carat weight diamonds with the same cut.

Diamond carat weight comparison

Please note that diamond carat weight is unrelated to gold karats, which is a measure of gold purity.


Last but not least, there is the cut of a diamond. Most people are not aware that cut is one of the most important C's. A properly proportioned cut is what gives the diamond its fire and brilliance. Acheiving the optimum table and depth are critical for superior diamonds. Don't confuse the cut of a diamond with the shape of a diamond! Each shape of diamond has its own ideal cut.

Illustration of proper and improper diamond cuts

Diamond Shapes

Diamonds are available in a variety of shapes. The shape of a diamond has nothing to do with its quality. The shape of a diamond is strictly a matter of personal taste and suitability to a setting.

Here are some of the many shapes in which diamonds are available:

Diamonds cut in various shapes