As far as standard interconnect go, Audio Sensibility has some of the absolute best solid-core silver interconnects (both RCA and XLR) if you are looking for something solid-core silver. However, there copper interconnects aren't that good and there are other brands that are better (in my opinion).
That being said, I have also read that you want extremely low capacitance for tonearm. The Audio Sensibility cables tend to use larger size 24awg or 26awg conductors. Even though it's silver, I'm not sure if this is optimum.
If I were shopping for tonearm cables, I might look at the Wire World tonearm specific cables and/or their inteconnects. They have multiple tiny awg isolated bundles of wire which make up the total cable. Their tonearm cables are advertised as 26awg, but they have 4 individual isolated bundles of 32awg conductors which should have a very low capacitance. You can go the entire range, from copper all the way to pure OCC Silver if you wanted.
I want to make a note that I don't have direct experience on tonearm cables, so take my comments only as stuff that I've read about.