Holloway Cut Advisor - Against a GIA Report? Help understand the Balance

[find45di2]

So I went diamond shopping and found a few diamonds that to the eye looked great. One of them turned out to rate poorly in the Holloway Cut Advisor.

Its dimensions were:
Depth- 62.1
Table-57 angle
Crown-35 angle
Pavilion-41.4
Cutlet-0

The GIA Report rates this an Excellent Diamond with a Very Good Polish and Symmetry.

So while this diamond looks superb to my eye and in the GIA Report, the Holloway Cut Advisor rates it as:

Light Return -Very Good
Fire - Fair
Scintillation - Fair
Spread - Very Good
TOTAL RATING - 4.8 - Good - Only if price is your main criterion


MAIN QUESTION:
So is this NOT a great diamond after all since the Holloway Cut Advisor says it rates somewhat lower on the scale with 2 fair marks? Should I only consider diamonds with a better holloway rating?

Help a newbie understand and make the right decision

 

[neatfreak]

Unfortunately GIA is often lacking in their definition of what an "excellent" cut is. Usually we tell people to listen to the HCA.

Just to clarify, this is a RB we are talking about right? HCA doesn''t work for other cuts, so I am just checking.

 

[find45di2]

Thanks for your response.

Yes, this is a Round Brilliant stone. I am a newbie so I had to think what RB stood for, for about 5 seconds

Anyone else have feedback on the GIA/Holloway differences?

 

[JohnQuixote]

Date: 8/6/2007 8:55:57 PM
Author: find45di2
Thanks for your response.

Yes, this is a Round Brilliant stone. I am a newbie so I had to think what RB stood for, for about 5 seconds

Anyone else have feedback on the GIA/Holloway differences?

The HCA penalizes the diamond you listed because of it's crown/pavilion combo, particularly the pavilion angle, which is quite steep. The pavilion and crown of a diamond must work in harmony to reflect/return light to the viewer's eye. If the combined angles are too shallow or steep the diamond is not as effective at returning light.

Here are simulated ideal-scope images for the diamond you listed above and a modern Tolkowsky make. You can see that the 41.4/35 combination has a ring where light is 'leaking' from under the table, creating an area of darkness in some lighting conditions (you won't see it in a jewelry store where the sheer volume of light overwhelms any subtleties of the cut), thus the score. The modern Tolk is an example of a diamond returning a healthy amount of light, with a nice balance of contrast, thus its better score.

Bear in mind these simulations assume perfect optical symmetry - but they illustrate why the scores differ.

 

[find45di2]

They were asking around $11,000 for this diamond.

Should I not consider this diamond any longer since its dimensions are not favored? I would rather pass and find something that is a better diamond overall.

It is interesting that GIA would rate this as an "Excellent" cut since it isn''t the greatest at returning light after all.

Feedback on the pricing is appreciated.

 

[ladyciel]

$11,000 for what size stone?

 

[Lorelei]

We need the carat weight, colour and clarity to be able to help with pricing, and to know what you are looking for, but I would suggest to keep looking unless as you say, you have seen this diamond you love it. The cut can be improved on and as you probably realise, cut is crucial for diamond beauty! As John has done the simulation for you, I would say as you think this rock looks great, compare it to some others which have an excellent cut and also look at the diamond in as many different lights as you can - hopefully the store will allow this. That way you will get an idea of how the diamond is likely to perform in ' real life' away from jewellery store lighting which makes most diamonds look incredible.

 

[neatfreak]

Date: 8/7/2007 3:00:36 PM
Author: Lorelei
We need the carat weight, colour and clarity to be able to help with pricing, and to know what you are looking for, but I would suggest to keep looking unless you have seen this diamond and love it, the cut can be improved on and as you probably realise, cut is crucial for diamond beauty!

I agree 100% with Lorelei!

 

[Ellen]

To me, I have enough info, I''d pass.

 

[Lorelei]

find4, the more I think about it, definitely compare this diamond to some others before you pull the trigger, make sure of what appeals to you and the difference in optical performance of this diamond compared to those with a better cut. If after this your eyes prefer the original diamond, then fine, but give yourself the opportunity to shop around and compare and see the differences for yourself before commiting. If you are new to diamonds and haven't seen many, then it is hard to know what actually looks good and what will remain looking good once away from the jewellers, so time spent comparing will be time well spent.

 

[kcoursolle]

I''d pass on the stone, you can definitely find a better performer. It is also important to keep in mind that the stone may have looked really nice because of the jewelry store lighting. Jewelry store lighting can be deceiving and make poorly cut stones look much better than they look in other lighting and can lead customers to make poor choices in stones.

 

[Fly Girl]

find4 - GIA Excellents can be either great or lousy on the HCA. You should use the HCA to weed out the lousy GIA Excellents. So, don''t buy this stone. Find a GIA Excellent diamond with an HCA score under 2. Then take a look under different lighting conditions. It should perform better than the one you are looking at now.

 

[Rhino]

Date: 8/7/2007 3:14:13 PM
Author: Lorelei
find4, the more I think about it, definitely compare this diamond to some others before you pull the trigger, make sure of what appeals to you and the difference in optical performance of this diamond compared to those with a better cut. If after this your eyes prefer the original diamond, then fine, but give yourself the opportunity to shop around and compare and see the differences for yourself before commiting. If you are new to diamonds and haven''t seen many, then it is hard to know what actually looks good and what will remain looking good once away from the jewellers, so time spent comparing will be time well spent.

Great advice Lorelei. Consumers here are sharing what has been taught and from what they are garnering from technology. We just need to bear in mind that technologies (especially the HCA) don''t always agree with human observation. The best advice is compare it to a stone with shallower pavilion angles, between the 40.6 - 41.0 zone. If you prefer that appearance that''s what you should get however it''s impossible for anyone (or even a technology) to predict what you may or may not prefer. In GIA''s observation testing many people liked the appearance of this stone just as you have expressed in your original post so it may be a good ideal to make the comparisons before you pull the trigger as Lorelei said.

Kind regards,

 

[Garry H (Cut Nut)]

Date: 8/7/2007 7:13:09 PM
Author: Rhino

Date: 8/7/2007 3:14:13 PM
Author: Lorelei
find4, the more I think about it, definitely compare this diamond to some others before you pull the trigger, make sure of what appeals to you and the difference in optical performance of this diamond compared to those with a better cut. If after this your eyes prefer the original diamond, then fine, but give yourself the opportunity to shop around and compare and see the differences for yourself before commiting. If you are new to diamonds and haven''t seen many, then it is hard to know what actually looks good and what will remain looking good once away from the jewellers, so time spent comparing will be time well spent.

Great advice Lorelei. Consumers here are sharing what has been taught and from what they are garnering from technology. We just need to bear in mind that technologies (especially the HCA) don''t always agree with human observation. The best advice is compare it to a stone with shallower pavilion angles, between the 40.6 - 41.0 zone. If you prefer that appearance that''s what you should get however it''s impossible for anyone (or even a technology) to predict what you may or may not prefer. In GIA''s observation testing many people liked the appearance of this stone just as you have expressed in your original post so it may be a good ideal to make the comparisons before you pull the trigger as Lorelei said.

Kind regards,

Many people = many people in the trade who participated and find those proportions to be quite profitable, so their opinions might not be yours. Also the testing was done in a light box that replicates a dealers desk lighting; Rhino likes this light box, but he is the only person I have ever heard who defends it. Several noted scientists have debunked it.

It would be very hard to find lighting situations of (other than over nuked jewel shops) where this diamond would compare well to other better proportioned diamonds.

It will have have a very small spread.

It will show the dirt far worse than a nice stone.

 

[find45di2]

Sorry for the late response, I do not get notifications of responses to this thread.

Here are all of the specs on this diamond since my question changed mid way to a price analysis.

GIA #15705479
1.60 carat
Color: F
Clarity: SI1
Cut Grade: Excellent

Polish: VG
Symmetry: VG

Round Brilliant
Dimensions: 7.48 - 7.53 X 4.66 mm


Also, the jeweler let me take the diamond onto the street and also turned on a fluorescent light, and the lights off, they definitely weren't trying to hide anything other than what the uneducated might not know.

THANKS FOR ALL OF THE REPLIES SO FAR!!!

So could $11,000 do any better for a 1.60 range stone, or something in the 1.50 to 1.60 range?

 

[Garry H (Cut Nut)]

Sorry, I dont do $ advice, but have you compared the diamond to other known to be weel cut diamonds, All diamonds sparkle - even uncut ones.
And have you sat it on your fingers rather than holding it up so light gets in the pavilion and out the top? If so can you see the skin thru the inner table region?

Ask to see the stone in some grey plasticine so it is ''dirtied''

 

[:)]

I would pass. It will likely look different outside of jewelry store lights.

no particular order:

$11051 (AGS 000)
http://www.whiteflash.com/round_ideal_cut/Round-Ideal-Cut-cut-diamond-161908.htm#

$11552 (AGS 000)
http://www.whiteflash.com/hearts_arrows/A-Cut-Above-H-A-cut-diamond-210360.htm

$10069 (AGS 000) (this one may be a great deal - check eye cleanliness)
http://www.whiteflash.com/hearts_arrows/A-Cut-Above-H-A-cut-diamond-179725.htm

$9077 (definitely call to ask about eye cleanliness) - this is an F - If eyeclean this is a huge bang for the buck
http://www.whiteflash.com/hearts_arrows/A-Cut-Above-H-A-cut-diamond-179725.htm

$10481
http://www.goodoldgold.com/diamond/3307/

$8980 (a FIC)
http://www.jamesallen.com/diamonds/I-SI1-Ideal-Cut-Round-Diamond-1087029.asp?b=16&a=12&c=77&cid=131

$9040 (**need to ask where girdle is very thin at**)
http://www.jamesallen.com/diamonds/F-SI2-Ideal-Cut-Round-Diamond-860637.asp?b=16&a=12&c=77&cid=131


$9078
http://www.whiteflash.com/round_ideal_cut/Round-Ideal-Cut-cut-diamond-311795.htm#