Did I make a mistake buying this stone?

[ChiTownSpecialK]

These are the stats on the center stone I purchased for my wife's engagement ring. This is a GIA certified stone. I came across the Holloway Cut Advisor on this site and I put the stone's info in just out of curiosity. I paid around $4500 for the stone in December 2010. It scored a 4.8 on the Holloway test. I thought I did ok but now I'm having second thoughts.

ROUND BRILLIANT

Measurements: 6.31 - 6.34 x 3.76 mm
Carat Weight: 0.90 carat
Color Grade: D
Clarity Grade: SI2
Cut Grade: Excellent

PROPORTIONS:
Depth: 59.4%
Table: 61%
Crown Angle: 32.5°
Crown Height: 12.5%
Pavilion Angle: 41.6°
Pavilion Depth: 44.0%
Star Length: 50%
Lower Half: 80%
Girdle: Medium, Faceted (3.0%)
Culet: None

FINISH:
Polish: Excellent
Symmetry: Excellent
Fluorescence: None

CLARITY CHARACTERISTICS:
Crystal

 

[Frenchcut]

What lab did grade this stone?

On PS it is often advised to choose a diamond that falls within these criteria regarding cut:

https://www.pricescope.com/community/threads/price.167194/

depth - 60 - 62% - although my personal preference is to allow up to 62.4%
table - 54- 57%
crown angle - 34- 35 degrees
pavilion angle - 40.6- 41 degrees
girdle - avoid extremes, look for thin to slightly thick, thin to medium etc
polish and symmetry - very good and above
(figures thanks to Gipsy - see thread quoted above)

I agree it does not look too good by the numbers, probably is too shallow, but what really matters in the end is the love it symbolizes. As long as you both enjoy this ring you shouldn't worry...

And don't forget that you can also choose to upgrade later when it's time to celebrate another milestone in your relationship!

 

[ChiTownSpecialK]

This is a GIA certified stone. I went on BlueNile to see what diamonds similar to this one were priced at and of course I couldn't find an exact match, but very close matches were priced more than this stone.

I understand the sentiment behind the stone but I'm trying to look at this objectively. I want to understand the details as best I can and I really don't want to be taken advantage of because of the emotional aspect of this purchase.

 

[Christina...]

The HCA is a rejection tool not a selection tool, it uses only four measurements and can't take others into consideration such as minor facet variations and cutters tricks. There are other tools that could be used to evaluate light performance, but you said that you thought you did a good job, and it sounds as though you and your wife both love the diamond. What the two of you think of it is much more important than what a few measurements ran through the HCA says about it. Enjoy your diamond, I'm sure it's beautiful!

 

[ChiTownSpecialK]

Thanks Christina. You are absolutely right. I'm probably asking a question where I only want validation. lol It is my nature to dissect, research, and think about purchases. Both my wife and I hate/love this personality trait of mine. There are times I just don't want to make a decision because I don't want to go through my "process". LOL

I realize that I will never be as knowledgeable as the people that work in a specific field, day in and day out, but I want to be as well versed as I can be. Now, I am trying to purchase earrings for my wife and I'm trying to build on what I know to make an informed decision.

 

[Christina...]

Good for you and such a lucky wife! We suggest that you look for stones that well cut as defined by GIA or AGS, as these are the most accurate and consistent labs in the world. Then run the measurements through the HCA rejecting stones that score over 2. Remember this is a rejection tool, there are of course beautiful diamonds that score above 2, but this is the safest way to purchase, especially online. Once you find a good scoring stone, you should ask your vendor for Idealscope images, this will further determine the performance of the diamond. (you can read more about idealscope and HCA under the tools tab) Lastly purchase your diamond and have it evaluated by an appraiser and of course by your own eyes!

If you'd like help selecting some stones, let us know, we'd be happy to help!

edit: opps I see you have another thread for the earrings and are getting lots of help! Good Luck, I'm sure that you will find some amazing diamonds!!

 

[Lula]

It looks like a nice stone. Its proportions are closer to a 60/60 cut than a Tolkowski "ideal cut." The Tolkowski cut tends to be preferred on this site, and it is easier to buy a stone sight unseen when the stone's proportions fall into the fairly narrow range of Tolkowski cut proportions. But well-cut diamonds come in many "flavors" that include both 60/60 and Tolkowski cut. In addition, your stone comes with a good pedigree -- it was graded an excellent cut by a reputable lab (GIA). So I would say you've done your homework, and it appears that you got a good price on a nice diamond. So enjoy your beautiful diamond!

 

[ChiTownSpecialK]

It looks like a nice stone. Its proportions are closer to a 60/60 cut than a Tolkowski "ideal cut." The Tolkowski cut tends to be preferred on this site, and it is easier to buy a stone sight unseen when the stone's proportions fall into the fairly narrow range of Tolkowski cut proportions. But well-cut diamonds come in many "flavors" that include both 60/60 and Tolkowski cut. In addition, your stone comes with a good pedigree -- it was graded an excellent cut by a reputable lab (GIA). So I would say you've done your homework, and it appears that you got a good price on a nice diamond. So enjoy your beautiful diamond!

Thank you Lula!

 

[ChrisES]

Your diamond is a shallow/deep 60/60 stone.

Take a look at this page: http://www.diamond-cut.com.au/03_inverse_relationship.htm

Your stone is very similar to the diamond that I purchased for my fiancee (also a D SI2, interestingly). Note that the HCA for your stone doesn't just give it a 4.8 but is specifically says good light return, fair fire, and excellent spread. As you've undoubtedly noticed, it should give off very white light in sunlight, and in spot lighting it should give off only very small flecks of colored light, or fire. It is a very particular type of diamond, but I'm a big fan of it myself.

If you look at the table at the bottom of the page I linked to and see the angle ratios that Garry has identified, you'll see that your stone is not the very best example of this style, as the pavilion is actually not as deep as it could be given the shallowness of the crown. So that's a minus. The HCA also favors smaller tables, by the way, so a portion of that 4.8 score is for the table size.

The above is to acknowledge that, even if you prefer white light / low fire stones (Garry calls it a "brilliant ideal cut") your stone is not perfect, but there is no doubt in my mind that you did not make a mistake either. I also think you got a good price on it (though in fairness I was not watching prices as long ago as December 2010). The real question I would have is about the clarity - especially with the large table, inclusions can be visible in an SI2. But SI2s can also be completely eye-clean. Clarity can't be judged by the numbers, so if you're happy with the clarity than I would say that I have no major concerns about the stone - although some posters who prefer more fire would disagree.

Congratulations on your marriage!

 

[John P]

If you look at the table at the bottom of the page I linked to and see the angle ratios that Garry has identified, you'll see that your stone is not the very best example of this style, as the pavilion is actually not as deep as it could be given the shallowness of the crown. So that's a minus. The HCA also favors smaller tables, by the way, so a portion of that 4.8 score is for the table size.

Hi Chris,

Actually the pavilion is already quite deep. An optimal inverse relationship would pair a shallower pavilion angle with a steeper crown angle. But this combination works as it stands; some of which is attributable to the 60-60 make. If the cutting is consistent with no aberrations I imagine the diamond is very bright. In addition to GIA EX that table/angle combination is a candidate for AGS2 light performance.

I'd also add that good 60-60 configurations do pretty well on the HCA. With 60D 60T you'll get favorable scores as long as the angles are strongly paired. For example, 60-60s with 33.5 CA return top results with any PA 40.4-41.0, and so on.

The HCA does (correctly) penalize steep pavilion angles, which is why there is a high HCA result for the diamond in-question. As an example, if ChiTownSpecialK's diamond had a 41.0 PA instead of 41.6 PA - all else the same - the HCA result would drop to 1.7.

 

[ChrisES]

If you look at the table at the bottom of the page I linked to and see the angle ratios that Garry has identified, you'll see that your stone is not the very best example of this style, as the pavilion is actually not as deep as it could be given the shallowness of the crown. So that's a minus. The HCA also favors smaller tables, by the way, so a portion of that 4.8 score is for the table size.

Hi Chris,

Actually the pavilion is already quite deep. An optimal inverse relationship would pair a shallower pavilion angle with a steeper crown angle. But this combination works as it stands; some of which is attributable to the 60-60 make. If the cutting is consistent with no aberrations I imagine the diamond is very bright. In addition to GIA EX that table/angle combination is a candidate for AGS2 light performance.

I'd also add that good 60-60 configurations do pretty well on the HCA. With 60D 60T you'll get favorable scores as long as the angles are strongly paired. For example, 60-60s with 33.5 CA return top results with any PA 40.4-41.0, and so on.

The HCA does (correctly) penalize steep pavilion angles, which is why there is a high HCA result for the diamond in-question. As an example, if ChiTownSpecialK's diamond had a 41.0 PA instead of 41.6 PA - all else the same - the HCA result would drop to 1.7.

Yeah, I clearly said that backwards. The chart shows a pav angle of 41.55 wants a crown of 30; since his crown is > 30 the ideal pav would be < 41.55.

Thanks for the correction.

 

[John P]

Yeah, I clearly said that backwards. The chart shows a pav angle of 41.55 wants a crown of 30; since his crown is > 30 the ideal pav would be < 41.55.

Thanks for the correction.

No problem. BTW, I thought your description of the optical qualities of this kind of diamond was spot-on.