Jump to content

Cut Grading Discrepancy Between Gia And Hca


Recommended Posts

I'm looking to purchase 1.53ct, round, F,VVS2, X cut, X polish, X symmetry (see below for specs). According to the latest rapapport, the price/ct is 16,300, which will put a 1.53 just below $25k. I'm able to pick this diamond up for $20k which is 20% under rap. This seems like a great deal considering for X cut diamonds, jewelers will charge at least 5-10% premium over rap. What I'm worried about is that this diamond didn't grade as well on the Holloway Cut Advisor (4.3 with 'good' in 3 of 4 catagories and 'very good' for spread). I was just wondering if anybody could give me their opinions on the cut of this diamond.


Here's the GIA cert that was just recertified with laser inscription (Jan 28, 2009):


Round, 1.53 ct

7.43-7.47 X 4.54mm

Color: F

Clarity: VVS2 (cloud & pinpoint)

Cut: Ex

Polish: Ex

Symmetry: Ex

Fluorescence: None

Girdle: Medium. faceted

Table: 59%

Depth: 60.9%

Crown angle: 33.5

Crown height: 13.5%

Pavilion angle: 41.4

Pavilion depth: 44%

Star length: 50%

Lower-Half Length: 80%

Culet: none



Link to comment
Share on other sites

There are more things in heaven and earth, HCA, Than are dreamt of in your philosophy.


The HCA works based on 4 numbers which are rounded averages of the proportions in 17 (or 18, including culet) facets out of 57 - plus girdle, and it has never seen the stone. GIA's grader has access to information about all the 57 facets and he/she has at least seen the stone. In addition to that, the HCA is based on Garry Holloway's personal preferences - which may not tally with yours or the conclusions of GIA's study on cut.


If you read the comment in the HCA it says "worth buying if the price is right". Using your numbers, which I'm not sure are correct (the Rap sheet is about as relevant to retail prices as the S&P500 is to an individual stock) is 25-30% off "market price" not enough to make it right?


Couple more thoughts:


1. The HCA is free. The GIA report cost at most $127 plus shipping - call it $200. The stone is $19800. You have looked carefully at the HCA, are dissecting the GIA report, but have you seen the stone? In different lights? In comparison to other well-cut stones? Yes, some of the angles in the report are "unusual", with a steep pavillion and shallowish crown, but that doesn't mean it's not a corker. Unfortunately, there's no way to know without having a look at the stone. Photos, ASET/IS photos, Gemex/ISEE2 reports would help, but are still not the final word (normalised lighting conditions are useful for comparisons, but not necessarily representative of real life).


2. Why focus on a VVS2 stone? A VS1 will cost 20% (or more) less, and will make absolutely no visual difference to you or anyone else, including people with loupes and keen eyes. A good SI1 would allow you to buy the setting, two wedding bands and a pair of diamond studs for the same price, and again it will make no difference to what you see, particularly once it's set (how many people have you seen that carry a loupe and want to check someone else's ring?).

Link to comment
Share on other sites

HCA is irrelevant for your application. Rap even more so. Chances are extremely high that this is a lovely stone, most GIA XXX’s are. The price is competitive as you can easily tell by comparison shopping using the ‘find online jeweler’ engine at the top of the page. Is it a deal? Possibly. That depends more on your criteria than on the diamond. A good price on the wrong thing is no bargain. If you started out looking for the best price on an 1.5+/F/VVS2/GIA/XXX, I think you’ve done well. If you started out looking for the prettiest diamond available for $16k, I think you may be able to do better, or at least bigger with the same visual appeal. The F/G and VVS2/VS1 boundaries are both important ones in setting the prices. How did you arrive at this selection criteria and, in particular, did this come from what the dealer wanted to sell or from what you wanted to buy?



Link to comment
Share on other sites

From my experience and testing thousands of diamonds for light performance using the most up to date equipment, I've found that stones with pavilions in the 41.4 degree area might not get the greatest light return. But each and every diamond is individual. There really is no substitute for checking this based on numbers only. I've at times had stones with great numbers that didn't do well and sometimes even stones without great numbers do well.


That is because there are 57 facets on a round brilliant cut diamond, and using only a few averages won't tell you what each and every facet is doing to return the light. You will need a brilliancescope test or Isee2 to tell you more.


Also every diamond is priced individually. Ever wonder why on the big websites that list 50,000 diamonds that not every 1.50 ct. VVS2 F runs the same price? That is because of the differences on the cut etc. Believe me the cheapest is not always the best.

Edited by jan
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Create New...