AGS 0 F/G differences- that much?!?

[purduephotog]

Afternoon-

Just returned from a fun venture this morning at another B&M. The place was very highly recommended from good friends, so I went on over and took a look anyway. I was impressed with the number of ''stocked'' diamonds available, so I took advantage to do some more scoping.

When he pulled out an AGS0 F the thing was on FIRE. Sitting next to it was an AGS0 G. The difference was palatable. Several other stones, AGS2/F all had the same sparkle and fire... whereas the G''s just seemed dull.

Is this expected? Or were the odds just stacked against me in this small sampling. I''m going crazy here (And probably ticking off Jennifer N., Tom, Denise N., and Barry) with my varying colour and sizes. You''d never know I made a decision with the way I''m waffling. Sigh.

So.... even tho side by side you can tell an F from a G, should it truly have that much affect on the scintillations? Or was I just ''unlucky'' in seeing this pattern (perhaps having my budget ''maxed'')

Thanks in advance

 

[oldminer]

There is way more variation within the AGS 0 range than one might hope for. This totally accounts for any visual differences you noticed. The slight difference from F to G color is something that your eyes could barely detect except in a properly set up grading situation, but never in jewelry store or outside daylight.

One wonders why AGS 0 has such latitude from superb to rather ordinary? Surely it pleases dealers, but many AGS 1 to AGS 5 diamonds actually perform better than low end AGS 0 cut diamonds. It is a matter of not balancing the faults found in diamond cut with proper visual results. In my AGA system, I used an approach that closely related appearance to cut grade especially in the top ranges of stones. More differences occur in the lower grades as the possible combinations widen, but at the top end of grading AGA is tight and AGS is not as well regulated a system. No doubt some diamond dealers or AGS members might disagree with this. I'd expect some would out of loyalty, wishful thinking or not fully understanding the facts. Nevertheless, I support the AGS attempt to help consumers by giving them a decent system that does part of the job. AGS has given the AGA Cut Class charts some nice press and we know that at some point part of both systems will go into new cut grading that we just don't have quite yet. AGA is not a perfect system either, at present. All of us hope for better tools and better understanding in the months ahead.

 

[JC]

Well put David. Thanks for the continuing education. It's always nice to learn from one of the best.

 

[pqcollectibles]

AGS0 covers a range of crown and pavillion angles combinations. Then there's the minor facets arrangements to consider as well. A diamond can look great on paper, but that must be confirmed by visual inspection, as you learned, first hand.

 

[purduephotog]

Thanks for the explanation, David- but that leaves me with one very important problem

How do I make sure my 'net purchased diamond falls into the 'good' catagorey?

Not to over emphasize, but there was such a severe difference between the good 0 and bad 0 that it's really got me 'freaked' out.

I'd hate to burn a couple of hundred on shipping each time to have a stone examined, and fail it.

grumble.

Thanks for all of your help.

 

[valeria101]

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On 6/11/2004 9:21:22 AM purduephotog wrote:




How do I make sure my 'net purchased diamond falls into the 'good' catagorey?

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Well... there is more to diamond optics than the AGS0 grade - a direct test of brilliance (rather than the AGS blessing) would approximate better your implicit definition of "ideal" ( = top brilliance, from what I read in your previous posts).

The good news? You are not alone in considering the AGS0 grade insufficient to represent the ideal diamond optics... many sellers here present their "ideals" (or whatever the name, if any) as a stricter selection based on evaluating the stones, not the numbers.

If between two equally brilliant stones you can still tell G from F face up, you outrun me by a mile

 

[aljdewey]

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On 6/11/2004 9:21:22 AM purduephotog wrote:





How do I make sure my 'net purchased diamond falls into the 'good' catagorey?

I'd hate to burn a couple of hundred on shipping each time to have a stone examined, and fail it.

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PP, this might be of help. Please know that it doesn't cost anything close to a couple of hundred dollars to ship a diamond. If it truly did, I could see where it would be more of a gamble.

The reality is that the vendor usually pays for the shipping to you when you may your purchase. If you decide to return it for any reason, you pay shipping. I recently sent a my ring from MA to TX to get it reset in a custom mounting. I insured it for $8800 (more than it was worth), and it cost me $18.45 to ship it insured via USPS. So you'd be out $20 or so if you bought a diamond online and it didn't thrill you when you received it.

To your question on how to pick one of the good ones.....pay close attention to the relationship between the crown and pavilion angles. The range of AGS 0 crown angles is 33.7 to 35.8. The range on the pavilion angle is 40.15 to 41.20. If you stick to tighter parameters (34.0-34.7 on the crown and 40.6 to 40.9 on the pavilion), you increase your chances of hitting the "sweet spot". That's what Dave was talking about when he mentioned that AGA grading is a bit tighter.

Within the AGS ranges, keep this in mind.....the higher the crown angle is, the lower the pavilion angle needs to be...and vice versa. If you pick a stone with a 33.7 crown angle, you don't want the pavilion angle to also be shallow. Conversely, if you pick a stone with a 35.3 crown angle (steep), you want a more shallow pavilion angle (40.5 or 40.6, for example). It's the relationship between the crown/pavilion that matters. It's like a yin-yang.

It's possible that the AGS 0 stones you were seeing in the jewelry store fell within the ranges, but BOTH the crown/pav angles were at the high end or at the low end, and that may cause them to appear less lively. Hope this helps.

 

[purduephotog]

An update on shipping costs:

It cost me 30$ to send a stone out for an opinion. When said opinion was rendered, tack on another 150$. Shipping back is another 30$ or 40$

So all told, an opinion has cost me 200$. Of course that opinion comes with a pretty damn good appraisal (*grin*) but still, I should have known what I was getting into.