I also have one of these. Though people refer to them as "Mexico Gold Fantasies," there's nothing magical or really fantastic about them. They also appear in various varieties. The link from CoinQuest below says it all: "These sell on eBay for less than $1 US dollar each. They probably have 22 karat gold plating, but the amount of gold in each piece is negligible. Value of a single coin is less than $1." Mexico Gold Fantasy Coin 1865
There are tons of them around, all dated 1865 and showing a bust of Emperor Maximillion. They exist in various degrees of detail. I have on that has an "S" mintmark which I have never seen on any others. pictures not mine
Much like @Conder101 mentioned I've seen similar examples that were minted in 8k gold. I have a couple of the other ones in that style, usually they are sealed up like this but not always as sometimes people remove them. I've also seen other examples that were pretty much just junk electroplated.