Re-cutting a diamond to improve proportions and light performance
My 2.03 RB (GIA Ex) gets a "Good" HCA rating and VG AGS, but changing the pavilion by only .2 makes it "Very Good" HCA and Ex AGS. In your professional opinion can the human eye even detect this .2 degree difference? Thanks for your time. – Kevin K.
Evaluating a diamond to be re-cut:
There are a lot of factors to take into consideration before deciding to have a diamond re-cut by Brian Gavin, or any other diamond cutter for that matter. Not the least of which is what the potential yield of carat weight is going to be after the diamond is re-cut, assuming of course that everything goes as planned, which is not always the case since diamond cutting involves taking a crystal and subjecting it to high pressure and extreme heat.
Without knowing the exact proportions of your 2.03 carat diamond, it is practically impossible for me to provide you with any insight as to what would be involved with fine tuning the proportions, but keep in mind that there would be a substantial decrease in value if the weight of the finished diamond came in less than 2.00 carats, because of the increase in price which occurs between the 1.99 – 2.00 carat marks.
Another factor which needs to be taken into account, are the inclusions which are present within the diamond, and you should be aware that the clarity grade of the diamond might change from being re-cut, depending on the nature of the inclusions, it could improve or become lower. Likewise, the color grade of the diamond is subject to change, since diamond color changes within the layers of the diamond crystal.
Needless to say, we will need the diamond shipped to us for physical evaluation before we can provide you with any accurate insight about whether the diamond has the potential to be improved by being re-cut. One of the things which we will with the diamond upon receipt is run a manufacturers Sarin report on the diamond, to determine the exact measurements for each section of the diamond, so that we have a better idea of what we’re working with and develop a plan for improving the diamond if possible.
What effect do proportions have upon diamond visual performance?
Earlier this week, a client asked me to provide him with an opinion on a diamond which he was comparing to a Brian Gavin Signature diamond, the diamond which he was looking at weighed 2.03 carats, was graded by the GIA with an overall cut grade of GIA Excellent, and had a total depth of 61.1% with a table diameter of 58% and a crown angle of 34.0 degrees with a pavilion angle of 41.2 degrees. Punch those numbers into the Holloway Cut Adviser and you’ll get a score of 3.1 Very Good, which Garry Holloway apparently feels is “Worth buying if the price is right” based upon the comment which follows the score; but if you drop just the pavilion angle measurement down to 41.0 degrees, then the score improves to 1.5 Excellent, which the comment then indicates is within range of Tolkowsky Ideal Cut (TIC) and the program indicates that the scores for Light Return and Fire improve from Very Good to Excellent.
The downfall of the Holloway Cut Adviser (HCA) is that it only takes the average measurements of the diamond into account and those are actually based upon the average of eight individual measurements per section.
In reality, the volume of light return, and the sparkle factor of a diamond, are going to look quite different between a diamond with those measurements, where the average 41.0 degree pavilion angle is based upon a low of 40.8 degrees and a high of 41.2 degrees, and a diamond where it is based upon a low of 40.6 degrees and a high of 41.4 degrees; and this premise holds true for the crown angle, star facet lengths, and lower girdle facet lengths as well… so it’s like one big moving puzzle, and adjusting only one angle on the diamond is akin to changing two spark plugs on an eight cylinder engine and calling it good.
However in this particular instance, it’s not likely that we would try to re-cut this diamond to improve visual performance, because any improvements that we try to make to the crown section are likely to decrease the crown angle below the 34.0 carat mark, and that would change the balance of brilliance and dispersion. If somebody wanted to improve a diamond with these proportions and carat weight is a factor (and it always is) then the best and most cost effective option is most likely to sell the diamond privately, and then buy a diamond which is already cut to the proportions which they desire.
By the way, of course the average person can tell the difference between a diamond with proportions of Good, Very Good, Excellent and Ideal, assuming that they take a moment to actually look at the diamonds, beyond the “Disneyland Effect” created by traditional jewelry store lighting, which pumps so much light into a diamond that crushed rock quartz is likely to look amazing! We sit down with clients all the time in our office, who ask this very same question, and who are easily able to distinguish the difference between diamonds of different proportions and cut qualities, by the volume of light return and sparkle factor.
