ID Metal 'Wrapped' Buttons

I have searched in vain and cannot find buttons like these on the internet. They appear to be a thin layer of gold colored metal that is wrapped around a solid core. This is most noticeable on the rear where the metal is a bit wrinkled and you can almost feel that there is space between the metal and what ever is in the center.
Any input would be appreciated.
Thanks a bunch!
Deb