Tolkowsky Hearts & Arrows Cut Diamonds on eBay
Danny, I've been reading your blog for awhile and really appreciate your advice. I'm trying to figure out the difference between a Brian Gavin Signature Hearts & Arrows diamond and a Tolkowsky Hearts & Arrows cut diamond that I found on eBay, if you could take a look at the diamond and let me know your thoughts, I would appreciate it. One other thing, the diamond is listed as being SI-3 in clarity and I'm trying to figure out whether that will be eye clean. Thanks! - Thomas J.
Diamond details as indicated by the seller on eBay:
Well Thomas, I took a look at the "details" provided for the diamond which is being advertised on eBay as an "Excellent Ideal - Marcel Tolkowsky - 8 Hearts and 8 Arrows" and looked up the details for the diamond grading report which was issued by The European Gemological Laboratory of Israel, and find it pretty unlikely that this diamond would exhibit a crisp and complete pattern of Hearts & Arrows based upon the measurements stated on the lab report.
According to the EGL-Israel, this diamond measures 7.35 - 7.44 x 4.57 mm and has a total depth of 61.8% with a table diameter of 60% with a crown height of 14% and a pavilion angle of 43% with a medium, faceted girdle with no culet size indicated. According to the EGL-Israel, the polish and symmetry grades of the diamond are excellent.
The clarity of the diamond is indicated as being SI-3 and the color grade is G with no fluorescence, however the lab report indicates that the diamond crystal is Type 1aAB, which is a gemological reference to the fact that nitrogen molecules are present in the diamond, this type of diamond crystal is often yellow and is often treated to improve the color.
Evaluating Diamonds By The Numbers:
The first thing which I noticed when I looked at the measurements for the "Hearts & Arrows Diamond" which you found on eBay is that the outside diameter measurements of 7.35 - 7.44 mm, differ by almost one full millimeter, which is a pretty substantial variation by Brian Gavin standards.
The next thing that I noticed is that the table diameter is a whopping 60% and the crown angle is only 14% which is pretty shallow, and these two factors eliminate this diamond in terms of being "comparable" to anything found in either the Brian Gavin Signature or Brian Gavin Blue collections because the diamond would not be considered to be a center range zero ideal cut diamond.
Diamonds cut similar to this one, are available through our diamond search engine by checking the box for the "everything else" category, which provides our customers to access to diamonds which are not produced by Brian Gavin, and which fall outside the parameters of our preferred selection criteria for proportions, polish, symmetry, and overall diamond cut quality.
Out of curiosity, I ran the measurements provided for this diamond through a program which creates virtual models of diamonds based upon the measurements, to see what the pattern of hearts and arrows might look like. Do you see how the arrow shafts for the arrows located in the 12 o'clock and six o'clock regions are faded out? The likely output of a 14% crown height with a 60% table with the 43% pavilion depth is a lesser degree of contrast which would cause the arrows of the diamond to be less distinct than the arrows pattern visible in Brian Gavin's usual production.
The fact that this particular diamond seller would refer to this diamond as an "Excellent Ideal - Marcel Tolkowsky" cut diamond is patently offensive because the measurements are blatantly beyond the parameters established by Marcel Tolkowsky, which called for a total depth of 59.3% with a 53% table diameter and a 34.5 degree crown angle which is offset by a pavilion angle of 40.75 degrees with a knife edge girdle. The table diameter of 60% and crown height of 14% is nowhere near this range!
The diamonds featured in the Brian Gavin Signature and Brian Gavin Blue collections, are produced to proportions which are within the center of the range designated by the American Gem Society Laboratory (AGSL) for their zero ideal cut proportions rating. This range of proportions is considered to be the modernized version of Tolkowsky which takes the girdle edge of a diamond into account, and is optimized using computer aided design to deliver a higher volume of light return than diamonds cut to the outer fringes of the zero ideal cut proportions rating.
In addition, the optical symmetry of our diamonds is superior by design, each facet is carefully aligned to ensure maximum contrast between the pavilion main facets which create the arrows pattern, and the sections of facets which comprise the remainder of the diamond, because contrast is what creates beauty and depth within a diamond.
My concerns with EGL and the SI-3 clarity grade:
The first thing to understand about the European Gemological Laboratory (EGL) is that unlike the AGSL or GIA, it is a franchise laboratory, meaning that it is possible to purchase the rights to use the EGL name and operate a gemological laboratory by whatever standards you see fit. I do not find their grading standards to be consistent, nor comparable to the grading standards and consistency provided by top tier gemological laboratories such as the AGSL or the GIA.
As such, maybe the diamond color of the diamond being offered by the seller on eBay is comparable to a G-color diamond as graded by the AGSL or the GIA, and maybe it is not... if my personal experience with EGL graded diamonds is an indication, it is doubtful that the diamond would receive a G-color grade if the diamond were sent to the AGSL or the GIA, my experience is that it will be graded as a much lower diamond color.
As far as diamond clarity is concerned, we don't recognize the SI-3 clarity grade because it is a clarity grade which is only used by the EGL, as a bridge of sorts to span what they perceive as a gap between the Imperfect I-1 and the Slightly Included SI-2 clarity grade, as used by the AGSL and the GIA gemological laboratories.
I rarely see an SI-2 clarity diamond which is eye clean and find it pretty easy to locate inclusions within an I-1 clarity diamond, so it is doubtful to me that this SI-3 clarity diamond would be "eye clean" from a distance of 9 - 12 inches, which is the industry standard for making that determination. If you truly want a diamond which is "eye clean" then I would select something with a clarity grade of SI-1 or VS-2 as determined by either the AGSL or GIA gemological laboratories.
Choosing a diamond from Brian Gavin Signature or Blue:
While I can see why the concept of this diamond is attractive from the perspective of description and price, I don't believe it is going to deliver the volume of light return and sparkle factor that you anticipate, based upon the fact that you are trying to compare it to diamonds featured within the inventory of the Brian Gavin Signature and Brian Gavin Blue collections.
While this is probably not your intention, you are essentially trying to compare a mid-range Volkswagen which is being described as if it were a turbo charged Porsche... apples and oranges. While it is possible that somebody who is not familiar with produce might mistake an apple for an orange because both are round in shape, the two variations of fruit are dramatically different in consistency, taste and smell.
I recommend using the search parameters available within the diamond search engine that is available on the Brian Gavin web site to narrow down the field of possibilities by whatever range of price you have designated for this purchase, and then limit the range of clarity between SI-1 and VS-2 to find options which will meet your expectation that the diamonds be eye clean.
Diamonds featured within the Brian Gavin Signature and Brian Gavin Blue collections are produced to the highest standards and are graded by the AGSL on their proprietary light performance grading platform, which ensures you of maximum light return and sparkle factor. Diamonds featured within the Brian Gavin Select category are not produced by Brian Gavin, but are filtered using a range of selection criteria that is more precise than used by the majority of virtual diamond dealers.
And by all means, feel free to contact us if you would like some recommendations based upon the range of characteristics that you would like to consider.
