About the size of a half-dollar and very very thin. A Google search on ACEAR, nothing. RACEA, nothing, ARACE, nothing. EARAC, nothing...,,, CEARA...BINGO! State counter-stamped issue for the state of Ceara in Brazil. I wonder how rare it is. Entry in Krause doesn't mention this issue, I believe it is a 40 Reis, but the ones they do list look valuable. I would call it an AU c/s on a VG host coin. http://books.google.com/books?id=K3...0CEIQ6AEwBg#v=onepage&q=ceara coinage&f=false
It's actually on a 20 reis host coin, and this is also a modern (false) counterstamp. This type is listed in Unusual World Coins and has a much lower collectible value than genuine antique Ceara c/s coins. One thing to note is how fresh the c/s looks compared to the highly corroded host coin. This is not what you would expect if the host and c/s were contemporary to one another.
Well, that's typical. The c/s Guadeloupe 2-bit (worth about 5 grand if real) was a fake too, -from the same collection. Thanks for the expert opinion, I concur.