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Help with HCA rating

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T

tr65

Rough_Rock
Joined
Jun 26, 2002
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17
Hi folks:

I wanted to stop first and tell you all that you have been a big help in my diamond hunting, thanks all. Now I have found what I think is a great stone so I got a Sarin analysis and ran it on the HCA. It comes back with a 2.6 very good rating.Light return and fire are very good and scintillation is good. Spread is excellent.

What does it all mean and what is scintillation?
 
Did you use crown and pavilion angles from Sarin report? You might want to post all the details so it'll be easier to discuss.[/u]
 
The crown angle is 33.8 and the pavilion angle is 41.2, the culet is .3%, table is 60.4% and depth is 60.2%

Girdle is thin to slightly thick and weight is .80 pts.

Sarin analysis says excellent proportion and symmetry.
 
Sarin can interpret the measurements based on different grading systems such as AGS or HRD. Which one was used in this case?

33.8° crown and 41.2° pavilion angles are within AGS ideal range but 60% table is not.

)[/u]
 
I have looked all over the Sarin analysis but it does not say anywhere whether it is AGS or HRD. One thing I did see that worried me was the table and the depth were both 60. Do any stones with a 60/60 look worthy of purchasing. The HCA comes up favorable, but fails to mention anything about the 60/60 rule. Is it that important?
 
).

HCA gives VG score: worth buying if the price is right. Is it? :)

If you comfortable with the price, then everything is all right.[/u]
 
Price is $2957.00 vs an H&A I am considering that is a .76 carat,VS1,G color, and ideal all over. The H&A is $350.00 more. Should I go with the H&A or the non-H&A. I mentioned it to the old miner and he called it a toss-up. Would you just get both and have him look at both? Help.
 
Only you can decide – depends on your preferences, taste and of course budget.

Ideally, you should look on both but that will probably cost you extra shipping...
 
Okay, thanks for the info. I think to be sure I'm gonna go with the H&A. Its only $350.00 more and I'm not paying to have 2 diamonds appraised. Does anyone else have any thoughts on the matter? I'm sweating thinking about pulling the trigger, but the relief will be great. You folks have been great and I look forward to sharing the outcome with you. Thanks again!
 
Have you thought about going for VS2 or SI1 clarity?

You won't see inclusions anyway but will be able to afford larger stone or just simply save some $.
 
Thanks Leonid for the advice. I had been comparing it to other stones that were VS2(which is what I originally wanted)but they kept being bought before I could get my hands on them. I was a little wary of an H&A stone at first, but have become more comfortable with them. I am currently awaiting the Sarin Analysis on the H&A before sending to an appraiser. Concerning the VS2 for good money, I just never could get everything I wanted for under 3 grand. So I decided to spend a little more for what I hope is the perfect rock. As I have told others, I'm only buying 1 rock in this life(so I want it to be the best I could find). I've done a lot of studying and listening from you guys/gals and have finally decided to pull the trigger.

I'll let you know the results from Sarin.
 
Sarin Results:
Light Return: Excellent
Fire: Excellent
Scintillation: Excellent
Spread: Very Good

Total Visual Performance: .7-Excellent-within TIC range

So far I am very pleased. Now its to the Old Miner for the appraisal.
 
I find it very interesting to see people talking about Sarin...

I am quite intimate with the machine, using it for rough and polished... As consumers you should not put too much weight in it. It's a necessary tool for professionals, but it is only one of many. The Sarin is not what you might think it is.

Funny story:
Had a chance to Sarin some GIA test stones used in their Diamond grading course. Let me just say that Sarin and the GIA official analysis were different. And what do you do - tell the guy doing his grading test to argue about the results with the GIA? I can imagine the conversation... "Oh ya... well the Sarin said...."

The best tool to judge a diamond is still your eye. Sure, some education goes a long way - bring knowledge to the table, but don't get too hung up on the nuances of Sarin, or even certs - aside from general the parameters (that these can be good for) you still need to use your eye.

cheers
 
1. Hey RB how do you think GIA work out a diamonds proportions? Answer = Sarin

2. Sarin also helped develop the GIA horizon system that allows them to pre-assess a diamond and identify from its proportions and other 'book-in' info if they have seen the diamond before. This helps them avoid those mess embarrassing court cases where they grade the same diamond years later and get a different grade.

(I secretly suspect that AGS and GIA have shared this data base, and so they miraculously always get the same grade, proving that they each grade with the same exactness!)

You might want to consider checking you instrument - do you have a calibration stone? We recently checked an Australian companies instrument and found that it was 1% out on tables.
 
I agree Cut,without Sarin how would you go about figuring the angles of the stone?
 
What RB means is that the Sarin number ned to be undertsood, and understanding 8 seperate bits of interacting data is more than a human can concieve - so it can be easier to look at the diamond.
But the 3 key bits of data can be entered into HCA and solve 90% of the riddle 99% of the time :)
 
Well , actually, NC, The GIA used to make a lot of noise about how their test stones were all hand measured etc.... I was talking about their test stones, not necessarily their certed stones - but I would also suggest that they don't rely on exclusively on Sarin here.

More on Sarin:
The technology is not perfect - the same stone measured twice on the same machine can produce different numbers.... there are many reasons for this including human error. Just because you have some Sarin numbers, that doesn't mean they are accurate. Someone asked about how crown angles etc would be measured then - the answer is by hand and eye my friend.

My recommendation is - Sarin is a great tool for the professional, and the data it produces is indispensable to the modern Diamond trader - yet, at a consumer level, show some caution regarding Sarin - don't take it as the be-all and end-all of what you're looking for. The data is only as good as the person selling you the stone. It can be spoofed, errors can be made, and misrepresentations occur.

edit to add:
I'll look into the calibration thing. We use two machines (one in Antwerp and one in North America). Don't get me wrong, I love Sarin - but unless you are intimate with by whom, how and where those numbers were produced, the consumer should
 
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