Chilean 1811 "Imaginary Bust" 8 Reales

First, quickly, re: the black stuff maybe coming off somewhat with acetone... That's more than simple organic gunk - not sure how much acetone would remove. Look at the effort it took to get it off the front. An awful scrubbing, of course, but you'd have to assume it was done like that because of how stubborn it was. AND, it appears to be worse on the back...

I also would say that the OBVERSE detail is pushing XF (we could call that MBC to MBC+) - I think it would snag a 35 to 40 from NGC. The problem is that there is now the effect of a true split grade, as the reverse has been more severely affected by whatever caused the black stuff. A good amount of reverse detail appears to have been lost to that. NGC or PCGS would likely average that out to "VF detail" - too much obverse there to call it only "F detail". This one calls for the old obverse/reverse separate grading.

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In terms of judging the problems vs the amount of detail and valuing accordingly... One thing - I actually loathe net grading (a la small white ANACS)... It's some vague attempt to objectively rate a problem coin in kind of an idiot-proof investment valuation manner. I think the only thing you can "generally" say with some specificity in terms of "grade" of a garden variety problem piece is the amount of circulation wear it shows... AND even that is hard specifically for sea-salvage and cases like this where one side was affected more than the other. Obviously objective points go into it, but it can't be perfect and exact. I'm glad to see that the "net grade" seems to be fading from use...

Anywho... jfransch, it's pretty obvious you would never even look at a piece like this at auction or otherwise... As such, it may be impossible for YOU in particular to judge an appropriate fraction of problem-free that this should trade for... but that really isn't the case for people who WOULD accept such a piece and do observe and maybe even seek out such pieces. If someone falls into this one of those camps, AND is familiar with the market for this coin type... a reasonable estimate is certainly doable. Very simply, you look at what historical trends are for specimens with commensurate levels of wear vs. decrapitation of types that fall into a similar range of rarity/popularity/price. An auction house, for example, would of course do exactly that.

Then we have the question of the tipping point of level of deduction vs. a problem-free piece where we should simply hold off for better... Now, you stated that you DON'T think there's NO market for this piece... BUT that question, by its very nature, intimates that there IS indeed a point where a piece becomes non-collectible - AKA, worthless. Problem-free, that's a 4-figure piece... Is a cull version REALLY not worth anything?

I know that you personally would really not consider this piece at any price... absolutely fine for your collecting goals. Keep in mind, though, that whereas this piece (despite being quite a rare/desirable type... and NOT the worst example ever) wouldn't fit your "proud to own" criterion... There are tons of collectors out there who are "proud" to own... um, maybe dreck El Cazador pieces, or a common cleaned/chopped F+ Charles IIII 8R. And, who knows, a few of those people may even be similarly advanced collectors who can still make room for certain types of culls. You are indisputably much pickier that that... and that is probably more noble, as "nice" specimens will outpace lesser ones if the market for that country or type really gains steam. Yet, are picky and coin snob somewhere on the same continuum? Did the chicken come before the egg? Did the tortoise beat the wabbit? Who among can judge these things?

"There is a more dangerous way to remove that crap... properly done electrolysis."

Yes, it can go wrong... but that's what I was thinking - probably with some decent acid involved (perhaps HCl). Given that the obverse is mostly clear of it now, I would want the reverse to match... but yeah, looking at what's there, COULD end up somewhat fried. You have to know what you're doing to even entertain the thought.

Perhaps if acetone doesn't do much, before resorting to electrolysis or similar, some white vinegar might be worth a shot.