So, after viewing diamonds online for 2 years and study what I can get online, I can summarize what I learned about the sweet spot proportions as below:
1. Table (<=56%) - Better fire. Table (>=57%) - Better brilliance. Personally I tend to prefer better fire, but I would also prefer wider table if the diamond depth is slightly on the shallow side. The pairing of deeper cut diamond with smaller table and the pairing of shallower cut diamond with wider table is what I have observed in those super ideal diamonds inventory, hence, I come out with this theory.
2. Crown angle (34.0 degree to 35.0 degree) and Pavilion angle (40.6 degree to 40.9 degree) - The steeper the crown angle gets, the more fire it will gain. As for pavilion angle, what is a suitable angle really depends on the crown angle, but in general, the range provided above, which is the range for ACA specs, is safe to pair with any crown angle between 34.0 degree to 35.0 degree. These 2 angles are the most important criterias in choosing diamond.
Always remember - Steep crown angle must paired with shallow pavilion angle while shallow crown must paired with steep pavilion angle. This being said, 41.2 degree is actually acceptable, it is actually the steepest pavilion angle you should get, but it comes with a caveat - it is advisable not to choose a steep angle like 35 degree because it is highly unlikely to work well. A 34 degree crown angle may work well instead because it is towards the shallow side. As for 34.5 degree crown angle, I will have to review the performance images first before I am willing to put my money down.
You can still see 41.4 degree pavilion angle diamond being graded as an GIA Excellent Cut diamond but this is one of those diamonds you should avoid. It will very likely to leak light most of the time, if not, then the crown angle will be very shallow to compensate for it, and this may cause the girdle to be very thin and may compromise the integrity of the diamond (meaning the diamond will be fragile).
Nonetheless, when hitting the sweet spot proportions like what that are stated in the ACA specs will guarantee you a decent performer with excellent IdealScope and excellent ASET. They are really the bullseye for excellent light performance.
If you are wondering whether there are any more things we can further narrow down to select a better diamond, there is one thing you can do - You can still apply the same principle of the inverse relationship of crown angle and pavilion angle within the tight proportions of an ACA! For example, I find that 34.3 degree crown angle, 34.4 degree crown angle, and 34.5 degree crown angle, when paired with a 40.8 degree pavilion angle. As you can see, those crown angles are towards the shallow side to the exact middle nunber (34.5 degree is the middle) of the crown angle on ACA specs, while the 40.8 degree pavilion is slightly towards the steeper side. I always think that the best relationship of the crown angle and the pavilion angle will exhibit a Hearts pattern similar to the one below in the diamond grading report:
Of course, this is really a bonus. In reality, ACA specs are really tight enough. Personally, I may choose a diamond with 34.7 degree crown angle that is paired with a 40.8 degree crown angle if the Hearts image is better than a diamond with 34.5 degree crown angle and 40.8 degree pavilion angle. Of course, this is not all, personally, I would also rely on the actual diamond video to see which diamond really captures my eye. If the 34.5 degree crown angle and 40.8 degree pavilion angle manage to capture my attention, it is highly likely that I will go for that instead of the very slightly better Hearts diamond. Again, personal preference. I also like 35.0 degree crown angle diamond that is paired with a 40.6 degree pavilion angle. Can't say no to some extra fire, technically. ;)
Another tip, but take it with a pinch of salt
3. Star Length (>=50%). I find that diamonds with star length 50% or more will exhibit more contrast, making the diamond look busier and subsequently improve the fire of the diamond. WhiteFlash has a minimum requirement of 48% star length, but personally, I find that higher star length gives me the necessary peace of mind that the diamond will exhibit more interesting sparkles. 52% to 55% seems to be an excellent choice. Using the actual diamond grading report, we can observe the contrast level of the diamond better. Below is an example of the ASET on the grading report that exhibits good contrast level:
I tend to favour higher star length when Brian Gavin Diamonds firstly release their Black by Brian Gavin Collection, I saw that most of the diamonds produced by them exhibit great contrast. I learned from Black by Brian Gavin because this collection is produced by one of the best cutters in the world - Brian Gavin, and Black by Brian Gavin is the pinnacle of his work. Nonetheless, as time goes by, more variances start to pop-up. Some Black by Brian Gavin starts to show lesser contrast in the ASET. Are those bad stones? Definitely not. Brian Gavin's stones are one of the top in the world and the Hearts are very precise. Just that personally, I still prefer 50% - 55% star length, regardless of the contrast level shown on the grading report. I am overly particular about star length because my 0.53ct F VS2 WhiteFlash ACA exhibits more white flashes than colour flashes and star length is the thing I suspect. Please take this with a pinch of salt as I am just relaying this theory based on my own experience. One point to take note is that videos do help on knowing the actual performance of the diamond. I have actually written a separate blog post regarding this.
At the end of the day, WhiteFlash ACAs represent some of the very top diamonds in the diamond industry. Although there are hit-and-miss sometimes, but with the largest AGS online inventory, you have quite some selection to choose from. Their consistency has certainly improved little by little, especially with the introduction of their best of the best Collection Series - excellent eye-cleaniless with excellent optical precision. Perfection? No diamonds are absolute perfect. But factoring in price, quality, return policy, upgrade policy, and absolute top-notch customer service, WhiteFlash is seriously good.
1. Table (<=56%) - Better fire. Table (>=57%) - Better brilliance. Personally I tend to prefer better fire, but I would also prefer wider table if the diamond depth is slightly on the shallow side. The pairing of deeper cut diamond with smaller table and the pairing of shallower cut diamond with wider table is what I have observed in those super ideal diamonds inventory, hence, I come out with this theory.
2. Crown angle (34.0 degree to 35.0 degree) and Pavilion angle (40.6 degree to 40.9 degree) - The steeper the crown angle gets, the more fire it will gain. As for pavilion angle, what is a suitable angle really depends on the crown angle, but in general, the range provided above, which is the range for ACA specs, is safe to pair with any crown angle between 34.0 degree to 35.0 degree. These 2 angles are the most important criterias in choosing diamond.
Always remember - Steep crown angle must paired with shallow pavilion angle while shallow crown must paired with steep pavilion angle. This being said, 41.2 degree is actually acceptable, it is actually the steepest pavilion angle you should get, but it comes with a caveat - it is advisable not to choose a steep angle like 35 degree because it is highly unlikely to work well. A 34 degree crown angle may work well instead because it is towards the shallow side. As for 34.5 degree crown angle, I will have to review the performance images first before I am willing to put my money down.
You can still see 41.4 degree pavilion angle diamond being graded as an GIA Excellent Cut diamond but this is one of those diamonds you should avoid. It will very likely to leak light most of the time, if not, then the crown angle will be very shallow to compensate for it, and this may cause the girdle to be very thin and may compromise the integrity of the diamond (meaning the diamond will be fragile).
Nonetheless, when hitting the sweet spot proportions like what that are stated in the ACA specs will guarantee you a decent performer with excellent IdealScope and excellent ASET. They are really the bullseye for excellent light performance.
If you are wondering whether there are any more things we can further narrow down to select a better diamond, there is one thing you can do - You can still apply the same principle of the inverse relationship of crown angle and pavilion angle within the tight proportions of an ACA! For example, I find that 34.3 degree crown angle, 34.4 degree crown angle, and 34.5 degree crown angle, when paired with a 40.8 degree pavilion angle. As you can see, those crown angles are towards the shallow side to the exact middle nunber (34.5 degree is the middle) of the crown angle on ACA specs, while the 40.8 degree pavilion is slightly towards the steeper side. I always think that the best relationship of the crown angle and the pavilion angle will exhibit a Hearts pattern similar to the one below in the diamond grading report:
 |
| Hearts image with best relationship of the crown angle and the pavilion angle (in my opinion). |
Another tip, but take it with a pinch of salt
3. Star Length (>=50%). I find that diamonds with star length 50% or more will exhibit more contrast, making the diamond look busier and subsequently improve the fire of the diamond. WhiteFlash has a minimum requirement of 48% star length, but personally, I find that higher star length gives me the necessary peace of mind that the diamond will exhibit more interesting sparkles. 52% to 55% seems to be an excellent choice. Using the actual diamond grading report, we can observe the contrast level of the diamond better. Below is an example of the ASET on the grading report that exhibits good contrast level:
 |
| ASET with Good Contrast. Notice the Blue Burst in the Middle. |
At the end of the day, WhiteFlash ACAs represent some of the very top diamonds in the diamond industry. Although there are hit-and-miss sometimes, but with the largest AGS online inventory, you have quite some selection to choose from. Their consistency has certainly improved little by little, especially with the introduction of their best of the best Collection Series - excellent eye-cleaniless with excellent optical precision. Perfection? No diamonds are absolute perfect. But factoring in price, quality, return policy, upgrade policy, and absolute top-notch customer service, WhiteFlash is seriously good.
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November 26, 2018
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