Try a google search for "coin mountings" too.
I found one that listed these sources:
Fuller & Son
151 Exchange Street
Pawtucket, RI 02862
Ph: 800-237-0043
Fax: 401-723-1720
WR Cobb Company
850 Wellington Ave
Cranston, RI 02910
Ph: 401-467-7400
Fax: 401-467-6152
A quick search of FMG's website only found cinch mounts for oval stones. I didn't find any coin mountings at all. There are hundreds of sizes of coin mountings to fit the hundreds of sizes of international coins and medalions. I think you'll need a firm that specializes in coin mountings.