Here is a comparison of the dates on an 1846 gold half eagle and your coin, and a comparison of the beaks on the reverse. The 6 looks off to me (and the other digits as well), as well as the beaks.
There used to be a Yahoo group called contemporary counterfeits. It may have migrated to the new format (iOS or something) when Yahoo shut down the groups. The mostly had info on British coppers and Spanish colonial silver but the talked about other stuff as well. I think @Colonialjohn was an active member and have seen him occasionally post here FWIW, my gut feel says it's a contemporary counterfeit, but this is a topic I don't know much about. Based on your pics, it looks like there could be some gold wash and the design is close but not exact. It will be interesting to see if it really is a CC
Here is a link to that group. I received an update last week, so they still must be active https://groups.yahoo.com/neo/groups...awNocGgEc3RpbWUDMTU3ODM2NjkwMg--?guccounter=1
If that had come into ANACS when I was in charge of Authentication (a LOOOOONG time ago) I would have called it a contemporary counterfeit. I still would. You might want to use a little acetone to get that glue off of the reverse.
Have you tried distilled water on the glue? I'd try that before I tried acetone. It might be sufficient and you'd be no worse off if it didn't work.
At first I wasn't sure. But after looking at the photos it appears to be a counterfeit. I considered the half cent planchet idea which would account for the very wide rims, but I don't know the minting process in 1846, and a point was raised about a larger planchet not fitting in the half eagle hub. Besides the date and the eagle head, the rim is all wrong. in 1846 $5 was a lot of money. And it takes considerable work and skill to create a die. But after that, copper blanks and gold wash is nothing. Except for someone very used to handling a lot of money, (who could feel the difference) the only problem is the very light weight.
As noted in Forgotten Coins in the World Section gold wash or gold plated contemporary circulating counterfeits favor a copper host. Silver or gold wash adhere to copper hosts better than brass or bronze as in French plated (i.e., brass hosts) counterfeits. This appears to be gold wash left in this area on the reverse. A simple XRF scan would confirm this observation. Should have good interest to gold collectors and a gold wash XRF confirmed scan obviously would help its sale on EBAY. John Lorenzo Numismatist