Buying a Diamond – Cut
The four C’s these days have grown to the six C’s: Cut, colour, clarity, carat weight, certificates, and country of origin. It certainly does not make diamond buying any easier, so here is an simple guide to understanding how to purchase a great diamond.
Cut, or Make as we say in the trade, is the least well understood aspect of diamonds yet it is the most influential in their overall brilliance. The biggest misconception in my opinion is the use of the word “size”. We are accustomed to buying things that come in sizes– shoes, dresses, gloves. It’s only natural then to wonder what size diamond you want to buy. Diamonds are referred to in carats and points. 100 points equals 1 carat. So we can refer to a half-carat diamond as either 50 points or o.50 carat. But carats and points are not units of size but rather units of weight.
How that weight is distributed is crucial to the overall look of the diamond, yet the great majority of diamonds are not well cut. That is, the proportions and angles used in cutting do not maximize brilliance. Which begs the question “Why would a diamond cutter do that?”.
The economics of the diamond business has developed so that the price of a diamond rises not only in proportion to its weight. Because larger diamonds are more rare, the price per carat also increases as the weight increases. That’s like paying $2.00 per pound for one pound of sugar and $4.00 per pound for two pounds of sugar. As such, certain sizes of diamonds became the natural dividing line for higher prices per carat, namely 0.25ct., 0.33ct., 0.50ct., 0.75ct., and so on. A jeweller could sell a 0.50 ct. diamond for considerably more that a 0.48 ct. stone because it was perceived as better because it was a full ½ carat. However the thing to remember here is that .50 carat is not a size at all. It’s a weight. So a well proportioned 0.48 ct. stone could appear larger than the 0.50 ct. stone (i.e. have a larger diameter, which is the perceived size) and also have more brilliance because it has better proportions. Most people conjure up in their heads a two-dimensional image of the top view of a diamond– in effect, a circle– a very sparkly circle, mind you, but a circle nevertheless. So they visualize a half-carat diamond as having a certain diameter. While shopping, a couple might expect that all the half-carat diamonds they look at will have the same diameter. After all, they are the same size, right?
Nothing could be further from the truth. The term “carat” is actually a unit of weight, and we buy diamonds based on price per Carat just as we buy steak in price per kilo. A carat is one fifth of a gram. So what the couple visualizes is two dimensional (breadth x height) while what they are buying is three dimensional (breadth x height x depth). Consequently, it is possible for three Half-carat stones to have three completely different diameters, or in other words to appear to be three different “sizes”. Take that a step further and you will see that a diamond that weighs 0.47 carat can have a larger diameter than a half-carat (0.50 carat) stone.
So which stone should you buy, which is the best? Many people would want the one that appears to be the largest, the one with the biggest diameter. But if they learned that the proportions of the diamond affect its brilliance, they might reconsider, especially if they learned that we know exactly the right proportions that will maximize a diamond’s brilliance. The diameter, depth, and in fact all the angles in the diamond can be manipulated to produce the perfect balance.
This perfect balance is called the Ideal Cut, and it is not as common as you might think.
