In general, because there is no hard and fast rule as design implementation also comes into play, copper will sound warmer and richer and silver will sound more revealing and transparent. Gold is also warm, like copper, but captures a bit more harmonic textures. Many companies will try to combine some of these attributes by combining them, ie. silver clad copper, gold clad silver, gold clad copper, etc. From my experiences, straight silver is a bit too bright for my system/tastes. I do find that I like silver clad copper and/or gold clad silver cables though. I have also heard systems where pure silver worked very well, generally in a system with warm speakers and electronic components.
I have not listened to platinum conductors, though I have heard carbon fiber conductors, which have many of the characteristics on copper IMHO.
I have not listened to platinum conductors, though I have heard carbon fiber conductors, which have many of the characteristics on copper IMHO.