My friend just went through this with her daughter, except she swallowed a dime. They did Xrays to find out where the dime was. Then they sent her back home to dig through poop till they found it. She never found the dime, and after five days they sent her back to XRay, only to find it had passed through her system.
If it doesn't pass, it can get stuck in his system somewhere and cause some serious problems. I am assuming it's gold? You probably need to call your ped. and find out what the toxicity of gold is. They may want you to keep an eye out for certain symptoms. Either way you're gonna need to call the doc. I know it seems simple, what comes in will come out, but sometimes it doesn't come out and it's best if they know where to start looking if something does go wrong.