HCA 3.0 but AGS 000

[LLJsmom]

Gypsy has said it before that AGS000 trumps he HCA but I never thought I would see one, believe it, and choose it over an HCA <1. (Honestly this is one of the prettiest, most fiery and sharp MRBs I have ever seen. And you can clearly see there is leakage.)

Can some of the cut experts help me make some sense of this? Is there anything on the report that would have indicated that it would be such a visually beautiful stone and such a performer? Thank you for any insight you can provide. Cause by my own negligence I might have dodged a bullet. If I ran the hca I might never have chosen it.

 

[bmfang]

A very interesting angle combo there @LLJsmom. Any pics of this stone?

 

[LLJsmom]

In bright sunlight in a dark car

 

[flyingpig]

AGS0 stones with such angle combos are not uncommon.
HCA favours shallow stones with good light return, and punishes steep and slightly deepish combos such as 35.5/40.8, and 35.5/41.0 which may have leakage here and there but excel in sparkle and fire.

The diamond you posted definitely has leakage (you captured it well in your photos) but it does not mean it is not pretty.

Here is another 35.5/40.9 that is AGS0, but scores above 2.0 in HCA
https://www.whiteflash.com/loose-diamonds/round-cut-loose-diamond-3202009.htm

 

[LLJsmom]

Indoors

 

[bmfang]

A very pretty stone. Beautiful fire coming out of it!

 

[gm89uk]

Beautiful stone. HCA calculated there is probably some light leakage at this combination. It is not wrong.

Doesn't mean it can't be beautiful. It's a useful thing for buying online, where you can't see the diamond, you'll be safer going HCA <2.

Not all HCA 3 diamonds suck and people may like that look, the theoretical leakage in HCA 3 in an otherwise perfect stone is subtle, like the one @flyingpig posted

 

[Karl_K]

When a diamond is well cut and optically aligned you can play closer the the edges and get a unique and great looking diamond. AGS0 can at times find these because it considers all the facets.
HCA does not have the resolution to find them.
There are some ags0 stones that the hca correctly downgrades however.

 

[Rockdiamond]

Great looking stone LLJsmom!!!
Leakage gets a horrible rap here on PS, when in fact it's an integral component of beauty in many stones.

Is there anything on the report that would have indicated that it would be such a visually beautiful stone and such a performer?

Also important to remember that AGSL, and GIA do not grade beauty.
You might be surprised at how many stones "flunk" HCA, yet are incredibly beautiful in real life.

 

[valeria101]

@Karl_K, would you care to make simulated ASET models for the two sets of proportions ? I am imagining minute slivers of green between the lower ends of the arrow shafts of the HCA reject, but ... it is just a guess.

Admitedly, I hardly see anything of the sort in the images ...

 

[valeria101]

Leakage gets a horrible rap here on PS, when in fact it's an integral component of beauty in many stones.

I am old enough to recall the notion of 'contrast leakage' being thrown around, but I do see that nothing came of it. Same goes for errata of optical symmetry, once mentioned as a good spice. No complaint about the exceptional results achieved in absence of such refinements !

Until we get to bid on the rough, I see no hope for such arts ...

 

[LLJsmom]

Thank you all for your comments and observations. I am grateful for all insight and opinions.

I don’t doubt the accuracy of the HCA. Numbers are numbers. I am just surprised that even with the leakage the HCA has factored in, the diamond is so pretty, fiery and lively. Honestly I could not see the leakage IRL. I did not see any spot that did not seem to light up. If I wore it everyday for the next two years I would probably be able to find it, but I won’t have that chance. In pictures, maybe you can see it better, but to me none of those spots seemed to stay dark. Contrast leakage??? Deteriorating eyesight?

It does show me that there are some important things not indicated by an HCA and I will probably continue to rely on AGS reports when searching for future stones. And quite a bit of luck played into me not running the hca on this stone.

 

[Rockdiamond]

The term "leakage" is basically a derogatory term, which in itself is misleading because the actual phenomenon can be a plus to a diamond. But like valeria101 I'm also old enough to have been pointing this out for more years than I can remember

 

[LLJsmom]

The term "leakage" is basically a derogatory term, which in itself is misleading because the actual phenomenon can be a plus to a diamond. But like valeria101 I'm also old enough to have been pointing this out for more years than I can remember

I get it @Rockdiamond
Maybe whatever I saw, maybe the contrast leakage, didn’t bother me. I couldn’t even identify it. I just knew it had to be happening cause of the report. Maybe someone else could see that IRL. I couldn’t And I’m ok with that.

 

[John P]

The HCA is not diamond-specific. "HCA 3.0" in an indication that many diamonds with the basic 57, 40.9, 35.4 averages will have reduced brightness. AGSL's position agrees with that. Their cutting guides predict proportions-targets near this combination will receive anywhere from AGS 0-4. Your specific diamond is a positive example at those numbers; faceted in a manner that kept it above the AGS 0 threshold.

 

[valeria101]

It does show me that there are some important things not indicated by an HCA and I will probably continue to rely on AGS reports when searching for future stones.

The other way around is also true. HCA admits some features that AGS rejects & at least merit some benefit of doubt ... The relation between the two standards gets highlighted on th HCA chart - there is a white boundary around the AGS Ideal range.

It has been a while, but I think that this category (HCA/AGS) includes stones with flashier arrows that also tend to turn black when shaded relatively less closely - the other kind of 'contrast' & quite a bit more.

Flavours ! I am not seeing as much talk about them now as on the Old Pricescope ... & it would work better now, IHMO.

 

[valeria101]

The term "leakage" is basically a derogatory term, which in itself is misleading because the actual phenomenon can be a plus to a diamond. But like valeria101 I'm also old enough to have been pointing this out for more years than I can remember

It has been a while !

All those years ago, I had just started to live in English & would not cringe at connotations on the fly; now, they are no longer lost on me, unfortunately ...

 

[Karl_K]

@Karl_K, would you care to make simulated ASET models for the two sets of proportions ? I am imagining minute slivers of green between the lower ends of the arrow shafts of the HCA reject, but ... it is just a guess.

Admitedly, I hardly see anything of the sort in the images ...

I could but it would not settle anything because of the numbers being averaged.
See John's post above. AGS0 to AGS4 depending on specifics for a diamond with those basic numbers that is all the hca takes into account.
I doubt the actual aset looks like this based on it getting 0 but these are what the basic numbers say.

 

[Rockdiamond]

Flavours ! I am not seeing as much talk about them now as on the Old Pricescope ... & it would work better now, IHMO.

Exactly!!!

AGSL goes way beyond GIA in terms of depth of analysis, as well as documentation in terms of cut. GIA is more likely to include stones most of us would reject into the EX cut grade, versus AGSL0.
But that does not necessarily mean AGSL's system is better than GIA's system for all buyers. They provide different flavors- and some prefer flavors accepted by GIA, which would be downgraded by AGSL.
But no matter how much we discuss it, there's an unquestionable and totally understandable preference here on PS for AGS over GIA.
I think it's important to point out there's two sides- which inevitably gets me in trouble

 

[valeria101]

Not exactly subtle ASET ... @Karl_K

I would have expected to see the l___ under the table in the photos, if not the crown pattern, so something gotta give.

 

[Karl_K]

Not exactly subtle ASET ... @Karl_K

I would have expected to see the l___ under the table in the photos, if not the crown pattern, so something gotta give.

It is one of those combos that small changes in angles and alignment makes a big difference.

 

[valeria101]

GIA is more likely to include stones most of us would reject into the EX cut grade

Noticed GIA EX diversity of taste while running some numbers recently, but have not dug up the official GIA documentation ...

... an unquestionable and totally understandable preference ...

I could never understand preferences ! For example, my favorite fragrance has been a box of ten for too long (The Library Collection - it kept growing over time)... Not only they are very different, but each is extraordinarily complex. If anything, the brand is unquestionable ! Do they understand Taste, or merely one market - where trying new things is the greatest game.

Of course, preferences are un-questionable. I never dissent, always digressing ... (not unlike C. Chong did from Library I to X). Of course, I love a few figures of style - WWW ("anti-thesis", writes YF), etc.

Why Stop Playing ...

Trouble - some. In fact, I do not have a thesis (PhD) - since they get anti-thes(ed) too fast !

Just a thought ...

 

[valeria101]

It is one of those combos that small changes in angles and alignment makes a big difference.

I have always asumed that this is how the borders of the HCA gradient map were chosen ... Is it so ?

 

[Karl_K]

I have always asumed that this is how the borders of the HCA gradient map were chosen ... Is it so ?

It worked out that way in many cases anyway.

 

[LightBright]

The term "leakage" is basically a derogatory term, which in itself is misleading because the actual phenomenon can be a plus to a diamond. But like valeria101 I'm also old enough to have been pointing this out for more years than I can remember

Hi, can you explain what leakage -is- rather than leakage and what it brings to the table visually? I actually love seeing some clear depth within a well cut and beautifully colored diamond and even glassiness because I feel I can greater appreciate "the stone itself"; that's why I like ovals, and old cuts; rather than simply the reflections of an MRB prism. Is that what you mean?[/QUOTE]

 

[Karl_K]

Hi, can you explain what leakage -is- rather than leakage and what it brings to the table visually? I actually love seeing some clear depth within a well cut and beautifully colored diamond and even glassiness because I feel I can greater appreciate "the stone itself"; that's why I like ovals, and old cuts; rather than simply the reflections of an MRB prism. Is that what you mean?

[/QUOTE]

There are 2 kinds of leakage in diamonds: leakage as in a window and virtual facets that partially or totally draw light from the pavilion, usually on the other side of the diamond. The second is far more common.
Leakage can be used to provide contrast, a well cut MRB has contrast leakage at a few points if it doesn't have painting/digging.
I use it in Octavia to provide contrast while increasing overall light return.