Whats Going On With This 5 Centimes Ceres Bronze Coin?

Just for the record, I'm stealing the pics, so future observers of this thread can see what we're talking about.



And my opinion: varnish, lacquer, glue, or some similar clear substance slathered over part of the coin. See the un-toned areas? That's where the lacquer is still sitting (or was recently removed, if it's not there any more). Where the coin was not protected by the lacquer, it has gone dark.

Just judging by the pics, I'd say the lacquer has been removed from the reverse, but is still there on the obverse.

Thanks. Laquer theory sounds very plausible!