|
The last of the 4C that we will talk about here is Cut. Diamonds in the rough do not have the sparkles that we see in a finished product. A diamond cutter's job is to cut a rough rock into a diamond with facets that will best reflect light. A diamond that reflects light well would be seen to have sparkles and fire. As explained in the Carat section, sometime cutters may sacrifice the beauty of a diamond in order to save carat weight.
Shape
First let's talk about the shape of a diamond. There are many different shapes to choose from. The most common ones are listed below in the diagram.
By far, the round cut (often known as round, brilliant-cut) is the most popular shape, with over 60% of the market share. If you are buying a diamond for investment purposes, the round cut is definitely the choice, because of its vast market compared to other cuts. If you are shopping for an engagement ring, personal preference will play a big part, but here are some tips that you should know: the round cut, due to its symmetry all around, usually produces the most sparkles and fire. The emerald cut, on the other hand, is usually cheaper than other cuts of similar carat weight, because the wastage during cutting is usually lower for the emerald cut.
The Princess Cut diamond is also an increasingly popular cut. See our cover article on the princess cut for more details.
Cut proportions
Proportion refers to the angles and dimensions of a diamond, and it determines a diamond's optical characteristics, that is, how much it sparkles. About a century ago a diamond cutter named Marcel Tolkowsky found the perfect dimensions for the round brilliant cut that reflects and refracts light most beautifully. This set of dimensions is called the "Tolkowsky Cut". This is also known as the "Ideal Cut", or the "AGS Grade 0" cut. AGS currently offers only a cut grade for round diamonds, and not for other fancy-shaped diamonds.
The ideal proportions are shown in the diagram below:
However, most diamonds on the market are not cut ideally, and there is a wide range of dimensions. Out of the 4 Cs, cut is the most complicated since it is not just one straightforward aspect of the diamond. The many dimensions and angles interact intricately together to bring glitter to the diamond.
For many consumers, buying a diamond with an AGS certificate brings peace of mind, because AGS measures all the dimensions of a diamond and simplifies all the cut proportions into a single grade.
AGS Cutting Grade Scale
| 0 |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
9 |
10 |
| AGS Ideal |
AGS Excellent |
AGS Very Good |
AGS Good |
AGS Fair |
AGS Poor |
GIA certificates are also very reputable, however it does not provide a cut grade in its grading report. They measure only the table percentage and depth percentage for the stone. That information might not be enough to determine if the diamond is well-proportioned or not, but in general a good range for the Table Percentage is 52% to 64%, and a good Total Depth Percentage is between 56% to 61%. The other two grades on the GIA cert that are related to the cut are Polish and Symmetry. Polish indicates how smoothly polished the surface is. Symmetry indicates whether the size and shape of the facets are even and consistent. To buy a GIA certified diamond with more confidence, you can talk to the retailer and ask for a
Sarin or OGI computerized proportions analysis. Try to ask for the full report instead of a small summary.
Or, you can see if you can get it appraised yourself. For example, online retailer Blue Nile will ship loose diamonds to you to be inspected, before they put it into a ring setting. So you should be able to get an independent appraiser to look at the cut proportions, and other aspects of the diamond too. Some unethical jewelers though might have an biased view, and might try to downgrade your diamond to promote their own, so try to find an appraiser who is truly independent.
For readers who want to learn more about Cut, you can visit "GIA's Online Series
of Articles on Diamond Cut".
|
