Is it ALWAYS good to go by the HCA cut advisor

[ShoppingForARing]

If the cut advisor shows 2 and above, is the diamond still worth getting? for what reasons and in what situations?


for Rounds is what I am talking about...

 

[ShoppingForARing]

it seems as though when I find the 4 C-s I want...and I go by the cut advisor, to get a score of 2 and below, my price jumps by a couple thousand dollars!



Garry said the following: "I would not rule our VG Pol and Sym, as that will braoden your list. but yes - HCA is designed to be used to reject stones over 2.0"


Would a VG Pol and Sym still score below 2 on the HCA cut advisor

 

[mercoledi]

The cut advisor only works for rounds, so you have the first part right! There are stones that are beautiful that will score above 2 on the HCA. Some of these are 60/60 diamonds which have a 60% depth and a 60% table. There''s also another parameter that can cause the HCA to be high but the stone to be totally great, but it''s escaping my mind right now. Hopefully Gary or Lorelei will help fill in the blanks. I know I''ve recently run some Tolkowsky ideals that got louse HCA scores and fell outside of GIA/AGS ideal.

But the short answer is yes, sometimes.

 

[ShoppingForARing]

Would a VG Pol and Sym still score below 2 on the HCA cut advisor?



it's unfortunate because I'm only limited to what the jeweler searches for in his database..all she wants to tell me is Excelllent Symmetry and Polish...she seems to harp on that...I feel as though I can find a better diamond without Ex. sym. and polish at a better price...what should I request then?

 

[mercoledi]

No, the HCA doesn't even input symmetry and polish. You should look for VG or better symmetry, there's a little more wiggle room in polish. Here's Lorelei's cheat sheet for buying RBs. You should be looking at the combination of table and depth percentages with the crown and pavilion angles. These are the measures that tell you how much light the diamond is capable of returning to your eye as brightness, fire (colored flashes) and scintillation (sparkle). Different combos give more/less fire or scint. Ideal cut stones will have great brilliance.

Is your jeweler sending you the stones you're posting? If you're willing to list your preferred specs and budget we may be able to find a stone for you from another vendor or at least give you an idea of what is possible.

This is a more promising stone than the others you've posted, but it's VS2; it has a crystal and a tiny cloud.

 

[Lorelei]

Merc gives good info!!

Also sometimes the HCA can ding a diamond for having a steeper pavilion angle, but in some cases the diamond can still be gorgeous, so evaluate it on the rest of it''s proportions and use Idealscope etc.

 

[dockman3]

Date: 8/13/2008 5:19:50 PM
Author: ShoppingForARing
it seems as though when I find the 4 C-s I want...and I go by the cut advisor, to get a score of 2 and below, my price jumps by a couple thousand dollars!



Garry said the following: ''I would not rule our VG Pol and Sym, as that will braoden your list. but yes - HCA is designed to be used to reject stones over 2.0''


Would a VG Pol and Sym still score below 2 on the HCA cut advisor

It doesn''t surprise me that the price jumps by that much when you get a diamond to score under 2. That''s because these diamonds will usually out perform any others that are above 2 on the HCA and you pay the premium for those ideal cuts.

However, like Merc said, 60/60 diamonds generally score above 2. I happen to have one of those diamonds that scored a 2.7 I think it was and its a 20/20 diamond. I happen to love that look. Ultimately let your eyes be the final judge.

Anything VG and above for sym and polish will be fine. They don''t need to be Ex, but its nice if you can get them. They affect light return the least out of anything the cut advisor takes into account, so I don''t know why your jeweler is harping on those.

 

[Regular Guy]

I think exceptions to using the HCA (to screen) are when you have better tools. To wit...a) an idealscope, to consider the actuals, vs the extracted measured hopefully correctly and projected performance, and/or b) an AGS0 option, where the same principles for light performance that the HCA are supposed to use on the diamond have already been applied, thus giving it a 0. Sometimes, it will be outside of 2, but in this case, generally, the 0 trumps it.

 

[Rhino]

Right on Ira.

The HCA is good in many instances but there are definitely instances when it isn''t, particularly when diamonds demonstrate a high level of Optical Symmetry (ie. H&A types). We recently acquired a diamond with very precise Optical Symmetry and had a 34.8/41.1 crown/pavilion combo (2.8 HCA score). The diamond is no less beautiful than other H&A types with 34.5/40.7 crown pavilion combos (1.0 HCA score). Live examination and technologies confirm (including but not limited to what you pointed out Ira). If I were using the HCA to select a diamond I would have passed this absolutely rare and beautiful diamond right by.

I''m not saying I''d recommend all diamonds over 2.0 ... not by a long shot but if there is hard evidence pointing to data that contradicts an HCA score, HCA takes a back seat everytime.

 

[kcoursolle]

There are some gorgeous stones out there that score 2.1-2.9. They aren''t super common, but worth considering sometimes. However, the HCA remains a great rejection tool. Another reason to buy something that doesn''t fall within 0-2 is if the price is spectacular. I personally wouldn''t want to sacrifice cut for price, but sometimes this is a reason to do it.