non magnetic and silver could be either stainless steel (heavier type) or aluminum ( a lighter type) Many times you can distinguish the two just by bouncing it in your hand a bit to determine weightiness (that's an old term I just made up, funny thing though, the spell check didn't turn red ; ) Also, you can use those gloves and glasses, and that grinder to determine type (SS=sparks, Al=no sparks), even metals with differing carbon content give off different type sparks when hit with a grinder Popular Mechanics - Google Books