The third C is the cut of the diamond. This is the most important parameter in evaluating the value of the diamond. If the some is cut too shallow or too deep it looses brilliance and fire, it would have a lot of dark areas across the stone. This is the first thing that people would notice when looking at a diamond. Most of our diamonds are Ideal cut or Premium cut, the difference between those two cuts are the depth and table percentage. Different manufacture and laboratories throughout the globe would call both of those two cuts Ideal. To the untrained eye it would be very difficult to distinguish between the two. Although some in the diamond industry would say that the Ideal cut is the best cut we thing that they are both very good. Most manufacture would much rather cut a diamond close to Ideal cut proportions in order to retain the most amount of weight from the rough diamond. There is almost always a way to cut any diamond to Ideal proportions, but the trade off would be weight and every point (100 points = 1 carat) counts. To put in perspective, in a $10,000 per carat diamond every point is $100 that means that if the diamond can be finished at 3.12ct with a very good cut or 3.01ct in an excellent cut the difference would be $1,100. In most cases when customers are in the market for 3ct diamond they would consider both examples and in most cases would go with the larger one for the same total price. We also include in the cut t he shape of the diamond (Round, Princess, Oval, Asscher, Radiant, Cushion). As a rule of thumb, in 0.70ct and above diamonds round are about 15%-25% more expensive than any other cut. The reason behind this is that the manufacture loses the most amount of rough when they cut a round stone. Another reason is that the demand is higher. This factor should be taken into account as well when working with a budget (as most of us are). Keep in mind that most diamonds, regardless of the shape, would have a beautiful brilliance when cut to perfection.
The clarity of a diamond is based on a scale from FL (flawless) and IF (internally flawless) to I3 (heavily included). FL-IF are clean diamonds and there are no imperfections within the diamond. VVS1-VVs2 (Very, very slightly included) – on those diamonds it would be virtually impossible to see any imperfections under a 10X magnifying glasses. On the larger diamonds, 1.5ct and above, those diamonds would be a good investment with a combination of D-F colors. VS1-VS2 are Very Slightly included diamonds. When you look at the diamond under 10X loop you would find the overall look of the diamond very clean and transparent although there will be some minute imperfections. SI1-S12 are the most saleable diamonds within the U.S. Those diamonds would have some different types imperfections that would be visible under 10X magnifying glasses. Most of the SI stones are eye clean (hard to notice the imperfections to the naked eye).
You should always keep in mind that seeing or not seeing an imperfection is a subjective matter. There are some types of imperfection, mostly black carbon, that might be visible to the naked eye. As a general rule the determination of a clarity grade is based mostly on the ratio of the mass of the inclusion to the mass of the diamond. It is safe to say that a 1 carat (ct) diamond and a 20ct diamond that have the same size imperfection would not be graded the same way. The lowest grade with in the gem quality diamonds are I1 and I2 those are mostly included diamonds. the imperfections of those diamonds are mostly visible to the naked eye. Some of the I1 stones can face up nice if the imperfection is off to the side of the stone making in prongable.
The fewer and less visible these birthmarks are the more valuable a diamond will be. The following chart illustrates the varying grades for Clarity.