Round brilliant question

[GeoAtl]

Good morning,

I am hoping to get help from some of the PS experts here. I am looking at 2 virtual stones here and am wondering whether they represent a good value:

1) round brilliant, new AGS 0, 1.22ct, eye clean SI2, H, 6.83 - 6.87 x 4.24mm, negligible fluorescence, 61.9 depth, 56.1 table, 40.8 pavilion angle, 35.4% crown angle and 15.3% crown %. Depending on whether I use the crown angle or the crown %, I get very different HCA scores -- does anybody know why that is? After all the discounts, this stone would come out to about $5,173.

2) round brillian, new AGS 0, 1.20ct, eye clean SI1, I, 6.81 - 6.84 x 4.21mm, negligible fluorescence, 61.8 depth, 55.4 table, 15.9% crown %, 35.6% crown angle, 40.5 pavilion angle. Depending on whether I plug in the crown angle or the crown %, I get HCA scores of 0.8 or 0.7. After all the discount, the price would be approximately $5,103.

Many thanks!

 

[JohnQuixote]

Date: 4/7/2006 10:17:49 AM
Author:GeoAtl
Good morning,

I am hoping to get help from some of the PS experts here. I am looking at 2 virtual stones here and am wondering whether they represent a good value:

1) round brilliant, new AGS 0, 1.22ct, eye clean SI2, H, 6.83 - 6.87 x 4.24mm, negligible fluorescence, 61.9 depth, 56.1 table, 40.8 pavilion angle, 35.4% crown angle and 15.3% crown %. Depending on whether I use the crown angle or the crown %, I get very different HCA scores -- does anybody know why that is? After all the discounts, this stone would come out to about $5,173.

2) round brillian, new AGS 0, 1.20ct, eye clean SI1, I, 6.81 - 6.84 x 4.21mm, negligible fluorescence, 61.8 depth, 55.4 table, 15.9% crown %, 35.6% crown angle, 40.5 pavilion angle. Depending on whether I plug in the crown angle or the crown %, I get HCA scores of 0.8 or 0.7. After all the discount, the price would be approximately $5,103.

Many thanks!

Hi GeoAtl,

Welcome to PS. You should always use angles rather than % with the HCA. The first diamond receives a 2.4 (this is because 40.8/35.4 is somewhat steep/deep). The second gets a 0.7 (it has a shallow pavilion). Be sure to read the usage warnings and information included with the HCA.

By the angles these diamonds will look different from each other. If both are supported by the new AGS report and earned 0 in light performance they are good candidates from an overall light output standpoint in brightness/contrast. Have you seen the AGS documents?

If you are working with a vendor who has them in-house perhaps you can talk to an onsite expert who can describe the differences to you.

 

[GeoAtl]

John, I appreciate the warm welcome and the explanation. The stones are virtual, so the vendor can't really get a description other than an "eye-clean" confirmation. I have seen both AGS documents and have read HCA disclaimers... I am obviously a complete novice and do not quite understand how with these proportions and a fairly poor HCA score the stones received AGS 0 certification.

Since I am buying these stones sight unseen, is the general consensus that it would be more prudent to let these stones go and look for the better proportioned/better valued ones or does the fact that they are AGS 0 all but assure me that their light return, fire and brilliance will be excellent?

 

[GeoAtl]

bump

 

[belle]

you need to make sure that the ags reports you are looking at are the NEW reports with the light performance grade. if the stone you are looking at gets a ''0'' in light performance, you can rest easy.

 

[GeoAtl]

Yes, these are both new (2006) AGS 0 reports. Does this mean that the relatively low 2.4 score on the HCA can be more or less safely disregarded? What do you mean about the value both stones represent right now?

 

[JohnQuixote]

Date: 4/7/2006 11:13:54 AM
Author: GeoAtl
John, I appreciate the warm welcome and the explanation. The stones are virtual, so the vendor can''t really get a description other than an ''eye-clean'' confirmation. I have seen both AGS documents and have read HCA disclaimers... I am obviously a complete novice and do not quite understand how with these proportions and a fairly poor HCA score the stones received AGS 0 certification.

Since I am buying these stones sight unseen, is the general consensus that it would be more prudent to let these stones go and look for the better proportioned/better valued ones or does the fact that they are AGS 0 all but assure me that their light return, fire and brilliance will be excellent?

Belle''s advice is good re: new AGS documents (with light performance assessement).

If you are considering diamonds outside a vendor''s onsite inventory I suggest asking the vendor to bring the diamonds in so he/she can provide a complete analysis before you make the purchase, if this is possible.

 

[He Scores]

Buying just from these listed factors is like buying a car and the closest you can look at it is from across the street. Based on this limited information, the only disernable difference is the very important bottom angle.

I''d opt for the one averaging 40.8 as it being closest to the 40.75 that is deemed "critical'' by most cutters rather than the one averaging 40.5.


Averages can be very deceiving however.


Bill Bray
Diamond cutter

 

[He Scores]

Just to make my point about the bottom angles, analyzed by BrayScore the deductions of a diamond with ALL main bottom angles at 40.5 would have a score that's 32 points lower than the one where they would ALL be 40.8. This is of course based on 1000 being the best and zero being the worst.

So to make things easier, you could have a diamond with a BrayScore of 901 and the other with a score of 863.


Bill Bray
Diamond Cutter

 

[He Scores]

Also to make my point about averages and why my BrayScore analysis doesn''t use them, I have never seen a diamond that has all the bottom angles on the exact same angle.



Bill Bray
Diamond Cutter