When shopping for a diamond, many people initially focus on carat weight or clarity. However, ask any gemologist, and they will tell you that Cut is the single most critical factor in determining a diamond’s overall beauty and brilliance. While nature determines a stone’s colour and clarity, a diamond’s cut is a direct testament to human craftsmanship.

How do I Know if a Diamond is Well-Cut?

When referring to a diamond’s cut grade, a scale of specific terms is used to describe the quality. An “Excellent cut”, for example, refers to a stone in which the facets are angled to allow optimal total internal reflection and refraction of light. This makes for a vastly more brilliant and sparklier stone. “Very Good” cut refers to near-ideal proportions, while “Good”, “Fair” and “Poor” speak of diminishing cut quality. The cut grade of a diamond is stated on its laboratory certificate, along with a detailed analysis of exact proportions, angles and depth percentages.

Why is it Important for a Consumer to Know This?

The cut quality of a diamond not only affects the perceived brilliance (beauty) of a diamond but also its value. Knowing what to look for in certification and the stone itself means you’ll be sure to get what you are paying for.

When viewing a GIA-issued laboratory certificate, be mindful of three aspects noted with the diamond’s specifications. These are cut quality, polish and symmetry. If a diamond has been awarded an excellent grading for each of these aspects, it is known as a triple excellent cut and is more valuable than a poorer cut specimen, even if the diamonds are identical in colour, clarity and carat weight.

Bear in mind that by far the most important aspect here is the cut grade. Polish and symmetry gradings are not nearly as influential on the stone’s appearance or price.

What if the Diamond isn’t Certified?

When there is no laboratory grading to guide you, some critical observation skills are essential. You have the right to investigate and measure any diamond before purchasing it, so feel free to ask your jeweller for a calliper. A round brilliant cut diamond weighing 0.50ct, for example, should have a diameter of or close to 5.20mm. If the stone you have in front of you measures smaller in diameter than this, it is a deep cut diamond, which means you are paying for size you can’t see from the top.

In extreme cases, poorly proportioned diamonds fail to bounce light properly. A stone cut too shallow creates a ‘fish-eye’ effect (where a dull ring of the girdle reflects through the table), whereas a stone cut too deep produces a ‘nailhead’ effect (a dark, heavy centre caused by light leaking through the bottom).

If in doubt, insist on certification or keep looking, because when it comes to purchasing a diamond, you deserve nothing but the best.

At Mark Solomon Jewellers, our diamond selection is truly a cut above the rest. We carry the largest selection of loose diamonds and diamond engagement rings under one roof in South Africa, including over 1,500 GIA-certified diamonds, all available to you at exceptional prices. Visit our showroom or contact our sales team for more information or to select the diamond cut for you.