The easiest way for /you/ to know ahead of time is an acid test. The easiest way for figuring out what to do is talk to your yard. Yes silver edges are all the same if the colour is silver. Do cut them clean. As in just leaving the slightest bit on the wire. If they are not clean boardsort wont take them.
I sort wires by ID codes and let my yard scan individual wires and they group up by code for me. At this point after years there are markings I've simply memorized by sight for sorting. Don't tell anyone but generally I'm not even reading them anymore. Lol.
Honestly it's repetition. Nothing more. I now know which ones are silver vs nickel vs tin vs aluminium etc from habit so neither I or my yard really need to do much scanning anymore. 12 lbs ag2 10 lbs ag3 etc and we just go with it.
And I'm quick to put aside anything I'm not 100% on.

Anything ended as clean, pure, silver I don't ship to boardsort. Most flat wire ends are

80/20 ag/ni. ± Or 30/70 ag/ni. ±
Nickel has a better glimmer to it when not polished.

I've only found clean ag in high end networking eq like wimax router hubs and portable media devices ie tablets and cell phones