Diamond Guide

Many people think of a diamond’s cut as shape (round, princess cut, oval diamond, pear shape etc), but what diamond cut actually means is how well a diamond’s facets reflect and scatter light and sparkle.

The grade of cut, developed by the Gemological Institute of America (GIA), also takes into account factors like the weight relative to diameter, the girdle thickness (which in turn affects its durability), symmetry and polish of the facets.

The ideal diamond is completely colourless. But even if it appears colourless, a stone may actually have slight tones of yellow or brown. The GIA grades colour alphabetically from D (colourless) to Z (heavily tinted).

However grades D to F are considered colourless and G to J near colourless. Some colour distrinctions are so subtle that they're not noticeable. Diamonds with a D grading are the most valuable, although price will still be affected by many other factors.

Natural diamonds are the result of carbon exposed to extreme heat and pressure deep underground, resulting internal characteristics called inclusions. Many of these won't be visible to the naked eye.

Evaluating diamond clarity involves determining the number, size and position of inclusions and how they affect the appearance of the stone. The closer to flawless, the better its clarity, and this will be reflected in the price.

The two most popular certification bodies are Gemological Institute of America (GIA) and International Gemological Institute (IGI). Both are well respected diamond grading institutions.

However, GIA tends to be more popular in the USA, while IGI is also very popular in Europe and Asia. IGI often offers faster and cheaper certifications. Many diamonds purchased from a diamond dealer or retail jeweller will already come with either one of these certificates included. Find out more about diamond certification.

As the world leader in gemological research, GIA is uniquely able to utilise over 60 years of scientific knowledge and technology to deliver the rough-to-polish matching confirmation for polished stones. GIA collects data and images for rough analysis.

Once GIA receives the polished diamond, GIA uses markers and data identified during the analysis of the rough to scientifically match the polished diamond to its original rough, confirming the diamond’s country of origin, often displayed on the diamond certificate.

As a material, there is no chemical difference between lab grown diamonds and organically grown diamonds. They are identical terms of physical appearance and properties.

In fact, it has only been recently that testing tools could tell the difference between laboratory grown diamonds and diamonds mined from the earth. The differences are in where it's made (including environmental and social impacts), product cost, and resale value of the diamond, which is considerably lower for lab grown diamonds.