I have no experience, so I'll just theorize here...non-magnetic stainless steel (300 series, typically used in medical applications) is also a poor electrical conductor. It would produce only a weak response from a metal detector, so that you could probably get away with a small quantity of it, depending on the sensitivity setting of the detector. If you plate it with gold or silver, you will increase the electrical conductivity, which would make it more likely to alarm.