I own silver speaker cables by ArgentPur and they are the finest sounding speaker cables I have ever owned! Solid silver speaker and interconnect cables are more typically found in the upper end lines of cable manufacturers. (not all silver used in cabling is the same for all companies) And also found in the internal wiring of upper end electronics. If you research various cable lines you will likely find a hierarchy of materials used.
Pure Silver Wire
If silver is so good to use why do we not see solid silver speaker cables? Price is not that high- 10ga diameter pure silver 6ft is just under $300. That makes a pair of speaker cables about $1,100 for material. I see the price of some of these cables on the market and $1,100 is a fraction of their asking price.