Need input on this diamond - 40x, Ideal Scope and Sarin Attached

[Garry H (Cut Nut)]

I missed this before Gontama

Date: 10/15/2007 9:07:49 PM
Author: gontama

Date: 10/15/2007 4:15:27 PM
Author: Garry H (Cut Nut)

Date: 10/15/2007 12:17:34 AM
Author: gontama

Date: 10/14/2007 10:31:24 PM
Author: abs100
Ellen and Diamondseeker:

Thanks again - I have been discussing this stone with WhiteFlash but I was looking for some additional perspective which you have shared with me already. I do have a new question which pertains more to the HCA and the overall light performance of a diamond. Earlier today it suddenly dawned on me that the Sarin report is giving me both the averages and the extremes for the crown and pavilion angles. I ran all four combinations of the extremes such as low pavilion angle and high/low crown angle as well as the inverse high pavilion angle with low/high crown angle and I discovered that many of the HCA scores were lower than the score I received when applying the averages. What is the general consensus - is it good enough to just use the averages or do I need to be worried about all of the combinations of angles when looking at the HCA? Put another way - is the light performance of a stone with ''tight'' cuts going to be better than one with more variance in the cut accuracies?

Thanks.

Andrew

HCA can only work with the averages. ''Combination'' means nothing as every stone comes with certain variance which can yield dramatically different scores when used individually. HCA assumes perfect symmetry and gives generally sound judgment for reasonably tighly cut diamonds like the J.

Everything else being equal, a less tightly cut diamond will not have better light performance and/or visual property than a more tightly cut diamond. Unless the variance gets pretty big however, it will have nearly zero negative effect. The J stone is tight enough not to worry about the variance.

Ladies and gentlemen.
Paper scissors rock.

It is clear from the ideal-scope image that that stone with a little variance in crown and pavilion angles has an inproper scan or a tiny table tilt. Either way there is nothing any mortal can ever detect.

If there was a real variance within the crown and pavilion angle then we would see this much variance in the ideal-scope image.

I have been discussing this issue at length in this thread
https://www.pricescope.com/community/threads/a-cut-question-to-garry-h-and-others.70491/

Garry, can you please explain how you determined where the max/min c/p angles are?
If opposite (c/c or c/p) sides compensate each other, ''my understanding'' is that regular IS does not show that.
Please enligthen me.

If you look at the model ideal-scope I made and the actual stone you can see how I made that judgement.

Some one else wrote they like to see some crown height (I call this verticle spread) and 34 is their lower limit for crown angle. If this stone had a table size that was 1% larger it could have exactly the same crown height and be over 34 degrees. We should be careful sometimes about our knat picking

 

[gontama]

Thanks Gary.

By the way, can you please look at the IS images the OP took for comment.
https://www.pricescope.com/community/threads/could-you-guys-help-me-to-select-one-from-these.69796/

I think OP is still waiting for someone to comment on that.

 

[gontama]

TO OP: I second John.

Though this stone may not have as much color light as the other one you mentioned due to lower crown angle, it is likely to come with more intese, stronger light return under certain light conditions than the other one, which also appeal to many. I think it is also a very bright diamond face up.

These two stnoes are different in personality. But I do not think one is better than the other. Just different. Ask your GF which one appeals to her. Then you can decide.

This is where I see a lot of value in HCA. Without it, it is hard to judge if the stone has a good c/p combo in cases like this.

 

[abs100]

I do appreciate everyone''s thoughts and feedback. I know this is a well cut stone and it certainly has plenty of brilliance, that is not an issue at all.

Unfortunately, my brother is not living near me so I have not been able to compare both stones side by side and I am going from memory only. It is possible that my memory is not serving me well, but I hope that is not the case as only a couple of weeks have past . . . A few here have suggested that I may not have given this stone a chance on its own merits and I suppose that may also be true.

At the time of my last post, I had looked at this stone under natural lighting conditions outdoors without shade, two different kinds of incandescent spotlights (one halogen and one not), and also typical indirect incandescent room lighting. Since my last post, I have looked at this stone under a few additional lighting conditions including a different halogen spotlight and also indirect incandescent spotlights. I have not compared this diamond to those at local jewelers and, other than Helzberg diamonds, nobody local carries stones anywhere near this quality so the comparison would not be meaningful to me.

What I have come to realize is that under the right conditions, this stone does have more fire than I at first thought (so I am giving it a chance), however, I still feel strongly that it has significantly less fire than the stone my brother''s fiance has. On the other hand, this stone most certainly has more brilliance or "white" light than that other stone. I also recognize that there is nothing wrong with that difference per se. However, my brother''s fiance''s stone has an incredibly powerful visual impact to the point that it almost looks "explosive" as it is bursting out with color and fire. In contrast, my feeling is that the stone I have here does not provide that same level of overall impact.

I may have a chance to do a direct comparison between the two stones this weekend. I will post more feedback afterwards.

Thanks again for the input.

 

[abs100]

I think Gary described it best when he talked about "gnat picking". Ultimately I compared this stone to a number of others and concluded it was an excellent diamond and definitively worth the money I paid for it. It actually has quite a bit more fire than I at first thought. John was also correct in his comments related to lighting and I have come to realize that this stone looks quite excellent under moderate and indirect incandescent flood lights up close and from a distance and, of course, is extremely lively under direct sunlight. It seems to have more contrast than others I looked at and, as gontama pointed out, it is quite bright. Ultimately, I am very happy with the purchase.

More importantly, I am now engaged and my fiance loves the ring

! That makes it all worthwhile. I still have to take some hand pictures with ring - will post as time permits.

I wanted to say that I very much appreciate everyone's advice and help through this process and I am sorry for seeming to be difficult and questioning so much along the way. I know that it was a result of my own lack of experience/knowledge combined with curiosity and a desire to understand better. For me this was a learning process and I have gained valuable knowledge I will certainly leverage in the future.

Regards,

ABS100

 

[Ellen]

Date: 11/27/2007 5:53:15 PM
Author: abs100
I think Gary described it best when he talked about ''gnat picking''. Ultimately I compared this stone to a number of others and concluded it was an excellent diamond and definitively worth the money I paid for it. It actually has quite a bit more fire than I at first thought. I have come to realize that this stone looks quite excellent under moderate and indirect incandescent flood lights from a distance and, of course, is extremely lively under direct sunlight. I am happy with the purchase.

More importantly, I am now engaged and my fiance loves the ring

! That makes it all worthwhile.

I do appreciate everyone''s advice and help through the process and I am sorry for being difficult and questioning - it was simply my own lack of experience/knowledge combined with a desire to understand better. This was certainly a learning process and I have gained valuable knowledge I will leverage in the future.

Regards,

ABS100

Congrats Abs! And uh, I think you owe us a hand shot Mr.

 

[JohnQuixote]

Date: 11/27/2007 5:53:15 PM
Author: abs100

I wanted to say that I very much appreciate everyone''s advice and help through this process and I am sorry for seeming to be difficult and questioning so much along the way. I know that it was a result of my own lack of experience/knowledge combined with curiosity and a desire to understand better. For me this was a learning process and I have gained valuable knowledge I will certainly leverage in the future.

Regards,

ABS100

ABS - So glad to hear the outcome. As you may have guessed, that''s the horse I was backing.

Don''t apologize for questioning. A major diamond purchase can be a very important event and human nature is to want to be 1000% sure. You''re far from the first to experience paralysis by analysis.

We''re grateful you came back to follow-up. Sometimes people express the stress only to find out it was not a big deal in the long run...but fail to come back and finish the story. Bravo!

 

[gontama]

Congrats! This diamond with medium to si thick girdle, which contributes to durability, maintanis a nice spread of over 6.46 mm/ct due to its relatively lower crown angle coupled with ideal range of table size 56%. I myself would not be reluctant to purchase this type of bright stone.