This might be a little way off what most members encounter but i had a friend who had a bag of stainless steel bracelets with gold soldered on to parts of them.I stripped the bracelets down as much as possible and then soaked the gold parts in hydrochloric acid for 24 hours with a boil to finish off and then fresh acid added and boiled again to remove the final traces. The yield for my friend was 10.7 grams of 18 carat scrap,not bad for something most people would throw away.