Thoughts on this stone please?

[act1980]

Would G colour show up much colour in a RB?

Has a good HCA score.

Video here: http://video.sanghvisons.com/RO190716/RO190716.html

 

[tyty333]

Can you get an aset or idealscope image?

 

[mwilliamanderson]

For a ring you should find a stone with an HCA between 1 and 2. That shallower crown would be better for a pendant or earrings. It may be fine but check advanced images as @tyty333 suggested to be sure. It’s a BIC-Brilliant Ideal Cut so it will produce more white light return than fire.

 

[act1980]

Thanks for the replies. Is brilliance better than fire? I suppose it’s subjective?

 

[mwilliamanderson]

Thanks for the replies. Is brilliance better than fire? I suppose it’s subjective?

Fire is the colored flashes that a diamond can give so. It’s quite beautiful so we usually suggest people go for a TIC-Tolkowky Ideal Cut. That provides a nice balance between brilliance and fire.

To do that you want to stay within the following parameters:

depth 60-62.3

table 54-58

crown 34-35 degrees

pavilion 40.6-41 degrees

Super Ideal vendors usually feature pavillion angles of 40.7 or 40.8 with crown angles close to 34.5. The closer you are to that the closer you are to Tolkowski’s Ideal. However anything within these given ranges can work. Just remember if you have a shallower crown, like 34, it will work best with a deeper pavillion like 40.9 or 41. Or visa versa if you have a steep crown, like 35, it will work best with a shallow pavillion, like 40.6.

I know this can be confusing initially but after you’ve looked at 100 diamonds or so it starts to make sense lol.

 

[act1980]

Fire is the colored flashes that a diamond can give so. It’s quite beautiful so we usually suggest people go for a TIC-Tolkowky Ideal Cut. That provides a nice balance between brilliance and fire.

To do that you want to stay within the following parameters:

depth 60-62.3

table 54-58

crown 34-35 degrees

pavilion 40.6-41 degrees

Super Ideal vendors usually feature pavillion angles of 40.7 or 40.8 with crown angles close to 34.5. The closer you are to that the closer you are to Tolkowski’s Ideal. However anything within these given ranges can work. Just remember if you have a shallower crown, like 34, it will work best with a deeper pavillion like 40.9 or 41. Or visa versa if you have a steep crown, like 35, it will work best with a shallow pavillion, like 40.6.

I know this can be confusing initially but after you’ve looked at 100 diamonds or so it starts to make sense lol.

Thanks for your reply!

I found this diamond within the ranges that you've specified but it only gets an HCA of 5.5 so I'm really confused

Diamond Certificate

www.diamondselections.com

 

[mwilliamanderson]

Thanks for your reply!

I found this diamond within the ranges that you've specified but it only gets an HCA of 5.5 so I'm really confused

Diamond Certificate

www.diamondselections.com

The depth is 62.7 which is outside the limit and the PA is 41.6 which is also outside the limit. Change those numbers to 61 and 40.8 and the score will be much better.

Depth can be 60, 60.1, 60.2, 60.3, 60.4.....and so forth all the way up to 62.3 but not above.

PA can be either 40.6, 40,7, 40.8, 40.9 and 41 only.

Here’s an example.

Diamond | 2.593 ct I VS2 A CUT ABOVE® Hearts and Arrows Super Ideal Round Cut Loose Diamond AGS Certified | 4104627

This Whiteflash A CUT ABOVE® super ideal cut hearts and arrows 2.593 carat I color VS2 clarity loose diamond is graded by the American Gem Society (AGS) Laboratories. | 4104627

www.whiteflash.com

 

[act1980]

The depth is 62.7 which is outside the limit and the PA is 41.6 which is also outside the limit. Change those numbers to 61 and 40.8 and the score will be much better.

Depth can be 60, 60.1, 60.2, 60.3, 60.4.....and so forth all the way up to 62.3 but not above.

PA can be either 40.6, 40,7, 40.8, 40.9 and 41 only.

Here’s an example.

Diamond | 2.593 ct I VS2 A CUT ABOVE® Hearts and Arrows Super Ideal Round Cut Loose Diamond AGS Certified | 4104627

This Whiteflash A CUT ABOVE® super ideal cut hearts and arrows 2.593 carat I color VS2 clarity loose diamond is graded by the American Gem Society (AGS) Laboratories. | 4104627

www.whiteflash.com

Thank you!

How reliable is the HCA tool?

 

[mwilliamanderson]

Thank you!

How reliable is the HCA tool?

It’s very reliable for weeding out bad performers! It’s not a selection tool though. This means once you’ve found a stone that scores 1-2 you still need to look at images, real photos, ASET, H & A and the Lab cert. to make sure it’s a winner.

 

[act1980]

How does this one look? It's within the ranges for Tolkowsky isn't it? But it get's and HCA of 2.7 and fire and scintillation are only "Good"

 

[mwilliamanderson]

Are you shopping online? What vendor? I’m happy to search for some potential stones.

 

[mwilliamanderson]

How does this one look? It's within the ranges for Tolkowsky isn't it? But it get's and HCA of 2.7 and fire and scintillation are only "Good"

Not quite. The table is too large. This is a 60/60 style diamond. Like the first one you posted it will fall short in the fire department.

 

[act1980]

Are you shopping online? What vendor? I’m happy to search for some potential stones.

Thank you! Yes, I'm looking at a company in Dubai called Fergus James.

 

[act1980]

Not quite. The table is too large. This is a 60/60 style diamond. Like the first one you posted it will fall short in the fire department.

So if the face up is larger thats what the problem is with the fire?

 

[mwilliamanderson]

So if the face up is larger thats what the problem is with the fire?

If not cut proportionally spready can be a problem just like too deep is a different problem. They can both effect light performance negatively in different ways. You can get the most spread safely by choosing a 40.6 or 40.7 degree pavillion and finding a stone with a thin to medium girdle. Otherwise stay within the parameters I’ve mentioned. With a 40.6 PA you could go up to 35.5 CA.

 

[mwilliamanderson]

Thank you! Yes, I'm looking at a company in Dubai called Fergus James.

I’m going to make dinner but I’ll have a look tonight or in the am and see what I can find. I assume you want 2.5 carat, FGH, VVS or VS? Correct me if I’m wrong.

 

[act1980]

If not cut proportionally spready can be a problem just like too deep is a different problem. They can both effect light performance negatively in different ways. You can get the most spread safely by choosing a 40.6 or 40.7 degree pavillion and finding a stone with a thin to medium girdle. Otherwise stay within the parameters I’ve mentioned. With a 40.6 PA you could go up to 35.5 CA.

Man it's confusing! You'd think that if a stone is triple ex then performance would be the same

Thanks for all your help, much appreciated!

 

[act1980]

I’m going to make dinner but I’ll have a look tonight or in the am and see what I can find. I assume you want 2.5 carat, FGH, VVS or VS? Correct me if I’m wrong.

Thank you! I'm looking for triple ex, between 2-2.5 ct, D-G, VVS-VS, None to faint flou. Thanks so much!

 

[mwilliamanderson]

Man it's confusing! You'd think that if a stone is triple ex then performance would be the same

Thanks for all your help, much appreciated!

Yes, it is frustrating. Unfortunately that is not the case. Many unsuspecting buyers are disappointed when they find out after the fact.

 

[mwilliamanderson]

@act1980 OMG I found one. I’ve been searching for half an hour. Most of the diamonds here are steep/ deep. Check this one out and I’ll look a little more.

 

[mwilliamanderson]

Here’s one more within the ranges and two that might work but check the HCA scores.

 

[act1980]

Thanks so much for taking the time to do this for me, much appreciated! The G 2.50 ct was 0.9 TIC the one I found was 0.8 BIC. As the scores are so close together would you really notice much difference?

 

[mwilliamanderson]

Thanks so much for taking the time to do this for me, much appreciated! The G 2.50 ct was 0.9 TIC the one I found was 0.8 BIC. As the scores are so close together would you really notice much difference?

I’d recommend mine because the stone is within all the recommended parameters. The shallow crown on yours will not produce fire in the same way as a crown between 34 and 35.

Yours may be fine for you and only your eyes will tell you if you like it. However, I can’t recommend spending all that money on a less than an ideal cut diamond. Does this company which offers virtually no ideal cut diamonds at least have a good return policy so you can see the stone and return it if you don’t like it?

 

[act1980]

Just found this one:


Got an HCA of 0.5 TIC. Visually looks barely any different to 2.50ct either

 

[mwilliamanderson]

Here’s a chart with AGS and GIA cut grades for diamonds with 56% Tables. You can see the 2.5 I found falls within AGS Ideal and Gia Excellent but this 2.27 you found gets GIA Ex but not AGS Id.

 

[mwilliamanderson]

Oops, here’s the chart.

 

[act1980]

Thanks for this. Whats confused me is that the HCA says the symmetry is V.Good but GIA states Ex

 

[act1980]

How do I get this chart please? I've also found a stone with a 58% table

 

[mwilliamanderson]

Thanks for this. Whats confused me is that the HCA says the symmetry is V.Good but GIA states Ex

I’m not sure what the HCA means when it rates symmetry. Here is the 58% chart.

 

[act1980]

Thanks so much for this! I found another stone but it’s VS2 and slightly smaller measurements. Still got a TIC score though!