Gold Colored Morgan Dollars

I've had three Morgan Dollars lodged in clear plastic holders with pins on the back for some time. Oddly enough I thought they were my wife's, but when I asked she though that they came from my family. I have a few otehr that I know came from my grandfather, but I'm pretty sure the ones in pins did not. At any rate, I finally got to looking at them last night, and knocked them all out of their plastic holders. Two of them had an odd tint to them which I though was just tarnish, but when I cleaned them up a little it turns out that they are actually gold colored. Anyone have any thoughts on this? My best guess is that they are real but plated somehow (perhaps gold) just for the sake of wearing as jewelry. The silver one weighs about 26.7 grams, the other two are a bit heaver (26.8 and 26.9 grams). Any insight would be appreciated.

Thanks!