Speaker cables of cooper, or silver :Pros/Cons

I have heard the comment many times on AG that speaker cables,and ICs made of silver sound analytical and bright whereas,cables made of cooper are smoother but less detailed,(or warmer) Is there any truth to this claim?? What about cables made of "platinum", or other exotic materials?? From personal expereince Analysis Plus Oval 12(cooper) speaker cable after a long burn-in period did sound smooth and musical. The Audio Magic Spellcaster 2 interconnect(silver) was bright, but possessed excellent dynamics and detail.