Question about HCA..."search by cut" v. "cut advisor"..

[Starry]

Quick questions about the HCA. When you do a "search by cut" the HCA numbers are provided. Who inputs these numbers? Is the "search by cut" tool more accurate than me just using the cut advisor and putting the numbers in myself?

 

[aljdewey]

Date: 7/19/2006 12:54:41 PM
Author:Starry
Quick questions about the HCA. When you do a ''search by cut'' the HCA numbers are provided. Who inputs these numbers? Is the ''search by cut'' tool more accurate than me just using the cut advisor and putting the numbers in myself?

When you do a search by cut, the HCA scores appear because all the numbers needed to go into the HCA score are provided.

The search by cut is slightly more accurate because it takes the exact girdle measurements into account when calculating the HCA. So, the HCA score reflects consideration of all attributes (albeit it on averages).

When you input manually, there is no place to input girdle information; rather, the girdle is assumed to be medium in all cases.

Does this make an enormous difference? No. You may get a score of 1.0 on a stone, and the same stone in search by cut may show a 0.9.....becuase it sees the girdle is thin instead of medium. The variance is nominal to the point of being fairly insignficant. Either way is fine.

 

[Regular Guy]

Al, two bits says you're right in the big picture, but wrong in the little picture (which was really Starry's question). I imagine only Leonid & company will be able to nail it.

Date: 7/19/2006 12:54:41 PM
Author:Starry

Is the 'search by cut' tool more accurate than me just using the cut advisor and putting the numbers in myself?

I'm betting the answer will depend on...what source for data you trust the most.

Take a case study (I just did a case study of one), with a WF 1.203G VS2, with certification from AGS, but not an ACA.

Numbers reported in the field in the search by cut tool yield .6 on the HCA, if you do the math, and that's the yield reported in the tool as well. But, if you go into the cert's data, you'll get a variance in the table size, showing it's not 56 but 56.4. This would yield .7 on the HCA, but, as you can see, that's not what's reported. In my 2 bits, I'm betting that no girdle data is reviewed at all.

The main question could be...do you trust the vendor's measuring...which I'm guessing is reported with their submission to Pricescope..or do you trust the cert. If you believe WF, they will tell you to defer to the cert, in the case of AGS. Alternately, when they present an option from GIA, you're probably better off going with the data WF reports.

But, bigger picture, and absolutely, for the first round study...take advantage of the search by cut's math done for you. It's a tremendous service done on our behalf.

 

[pricescope]

Hey guys, in "search by cut" we are getting the data feed from the vendors where crown and pavilion angles are available in addition to usual numbers . This allows automatic calculation of the HCA scores.

Don''t be hook up to each digit though. There might be some rounding (angles, table size) and also small differences between AGS reports and in house Sarin/Ogi measurements. These variations should be within some acceptable level of accuracy but can affect HCA results depending which number you plug there.

If you see really big difference in HCA (e.g. >0.5) then check it out with the owner of the stone to found out the source of an error.

hope this helps

 

[aljdewey]

Date: 7/19/2006 2:31:58 PM
Author: Regular Guy
Al, two bits says you're right in the big picture, but wrong in the little picture (which was really Starry's question).

Honestly, Ira, I don't think so.

I'm fairly confident I understood what Starry's question was......and that's what prompted my answer.

I see what you're getting at (using data from the Sarin or other source could alter the results), but if that were the intent, I think the question would have been "which set of numbers is best to use?"

Given that it wasn't, I'm thinking I was on the right track initially.

As phrased, the question asked implies she would be manually data from the same source the "cut quality" search draws from.