Is the cut advisor reliable?

[fabulous]

I was talking with customer service at Blue Nile yesterday, and when I mentioned the cut advisor, he scoffed, and told me it was a crock of sh#t...is this true? I am looking at 3 different stones...two come out as excellent on the advisor, and the other only comes out as very good. What is the real deal here people?

 

[Lorelei]

Date: 4/17/2008 9:54:27 AM
Author:fabulous
I was talking with customer service at Blue Nile yesterday, and when I mentioned the cut advisor, he scoffed, and told me it was a crock of sh#t...is this true? I am looking at 3 different stones...two come out as excellent on the advisor, and the other only comes out as very good. What is the real deal here people?

How charming

. Did he actually use those terms??? No it isn't true at all. The cut advisor is extremely useful for eliminating lesser performing stones, especially out of the overwhelming amount to choose from on the virtual listing. It should not be used to select diamonds, as it is estimating how well a certain set of proportions may work together, but if it is used as intended, to eliminate the lesser performing diamonds, it is a very useful tool indeed.

The deal is this. If searching for a diamond, you can use the HCA especially amongst the virtual non in house stones, to narrow down the ones which may be worth further consideration. In some cases, this means rejecting diamonds which score over 2, so you concentrate on those which score 2 or below. Once you have your selections, you then evaluate with Idealscope and hopefully skilled vendor advice. With in house diamonds, often the cut analysis has been done for you, so the HCA can take a backseat to the other technologies which can help assess cut quality. In some cases, diamonds which score over 2 can be beautiful stones, so this is where a skilled and knowledgeable vendor can be very useful to guide you. Also again with the excellent and very good scores on the HCA, remember the advisor cannot actually see the diamonds and that to properly judge each diamond, you really need to use the Idealscope image and your vendor expertise, and ultimately your own eyes.

This info might be useful too. http://diamonds.pricescope.com/ideal.asp

 

[dmus]

Thanks for the link Lorelie. Here''s quote from the link.

"HCA is only for round diamonds with known Table, Crown, Pavilion and Total Depth inputs; it has no idea about the diamonds symmetry, poor minor facet proportions or various cutters tricks.
Use it to reject known poor performers and narrow down your selection. Please do not use it for final selection; it will not replace an analysis with an Ideal-scope and/or an independent appraisal."

I take this to mean it is a rough measure to be used as a general guide, but verify, verify because many important factors aren''t used in the calc. Actually after browsing here for a few months I don''t use the HCA that much. I can tell by the measures provided. However, when I get some strange pav/crown combinations or I have any doubts about the depth I would consult here or seek idealscope or ASET to make final judgement.

Gary, by the way, not to put you on the spot but have there been any studies with actual diamonds that back up the relative measure of a diamonds perfrmance via HCA to real life observations and other light perfoerming meassures. I must admit I have my doubts about the HCA as well but am not experienced enough to back it up with real life experience. Thanks.

 

[Lorelei]

Date: 4/17/2008 10:40:07 AM
Author: dmus

Thanks for the link Lorelie. Here''s quote from the link.

''HCA is only for round diamonds with known Table, Crown, Pavilion and Total Depth inputs; it has no idea about the diamonds symmetry, poor minor facet proportions or various cutters tricks.

Use it to reject known poor performers and narrow down your selection. Please do not use it for final selection; it will not replace an analysis with an Ideal-scope and/or an independent appraisal.''

I take this to mean it is a rough measure to be used as a general guide, but verify, verify because many important factors aren''t used in the calc. Actually after browsing here for a few months I don''t use the HCA that much. I can tell by the measures provided. However, when I get some strange pav/crown combinations or I have any doubts about the depth I would consult here or seek idealscope or ASET to make final judgement.

Gary, by the way, not to put you on the spot but have there been any studies with actual diamonds that back up the relative measure of a diamonds perfrmance via HCA to real life observations and other light perfoerming meassures. I must admit I have my doubts about the HCA as well but am not experienced enough to back it up with real life experience. Thanks.

Thats right.

And you are welcome!

 

[niceice]

Date: 4/17/2008 9:54:27 AM
Author:fabulous
I was talking with customer service at Blue Nile yesterday, and when I mentioned the cut advisor, he scoffed, and told me it was a crock of sh#t...is this true? I am looking at 3 different stones...two come out as excellent on the advisor, and the other only comes out as very good. What is the real deal here people?

LMAO

As suggested, use the HCA as a tool to help you eliminate poor performers from the list of diamonds you are considering. Then ask each seller for a facet-by-facet report from a Sarin / OGI / Helium so that you can determine the consistency of the facet structure. The HCA takes the average measurements for crown and pavilion angle into account, but the spread between the high and low measurements is not known and therefore there is room for error - but it still serves the general need to be able to weed out poor performers from the list of potential diamonds so that you don''t need to request a zillion Sarin reports to figure out the same thing, the HCA can help you figure it out in seconds.

 

[strmrdr]

The simplest way of putting it is that the HCA is a good filter too sort out which diamonds too get more information on.
It isn''t perfect nor 100% but it works for that use if the precautions are paid attention too.
http://diamonds.pricescope.com/ideal.asp
If you already have an IS or ASET image then the HCA becomes irrelevant.

Newer research shows it is a little too harsh on some combinations with pavilions slightly over 41.
But overall it is a useful tool when properly applied.

 

[fabulous]

I''m not sure that Blue Nile can provide those for me. I''m kind of set on one of their settings...a 18K WG 3mm band with 1/2ct of sidestones, and they don''t sell them seperatly, plus nobody else seems to have a setting I''m partial to at all... Another thinkg I have to consider is that I''m in Canada, and a lot of the other vendors don''t have a Canadian site, and have quoted a lot for shipping/ duty to me...in the range of $300-600, and BN only said it would be $180.

 

[niceice]

Date: 4/17/2008 1:05:55 PM
Author: fabulous
Another thing I have to consider is that I''m in Canada, and a lot of the other vendors don''t have a Canadian site, and have quoted a lot for shipping/ duty to me...in the range of $300-600, and BN only said it would be $180.

This is interesting because we never collect the Canadian import / excise tax, it is usually collected by the delivery agent. I suggest contacting the customs department in your area to determine what the amount of tax will be. We ship a lot of packages to Canada and the cost of insured shipping is not much more than shipping a package of that value within the U.S. I imagine that some of our competitors may be charging a special handling fee for international shipments (?)

 

[honey22]

This makes me so mad! I actually met with a jeweller when looking for a stone for my ering, and when I mentioned that I wanted to write the stats down so I can run it through the HCA - he said something along the lines of - that's just crap and our dear PS friend the inventor was a tosser!

(He actually used his name but I couldn't bring myself to type it.)

I nearly leaned over the table and smacked him one! Tools such as the HCA and education such as PS are fantastic!! They help normal people like us who love sparklies learn how not to be ripped off, and get the best looking diamonds for our money.

I think it just comes down to professional jealousy - if only they had been as brilliant as Gary and invented the HCA etc, they would a lot more open to the idea I am sure. Their loss.

All hail the HCA

 

[WinkHPD]

In a private conversation a friend of mine put it this way, I think it is brilliant enough to just quote rather than to try and paraphrase.

Quote:

Yes, the HCA has been backed up by observation. In fact it received a US Patent and is in-use by some factories when making decisions in rough planning. The “cutter’s line” concept used in the HCA was mimicked in GIA’s two-dimensional cut grading system. However, the HCA is more discriminating and penalizes some of the extreme steep/deep combinations the GIA (in a fit of insanity) permits to earn EX.

End Quote.

Frankly, it is another one of many many tools that we use in this industry to bring some understanding and clarity to the buying public. Any such tool is to be used with considerations to it's strengths and weaknesses, and it seems a shame to denigrate any tool that helps to make this very complex subject more understandable.

Wink

P.S. Here is an article in Rapaport with more details about the patent http://www.diamonds.net/news/NewsItem.aspx?ArticleID=18544