Before I realised (thank you , kind members of this forum ) that I could solder on a jump ring or wire, I bought a bit of bearer wire to try out. I've cut it very carefully, using a mitre cutting jig and set square, checking that all angles were 90 degrees, that there were no burrs, that both ends were identical, but every time, and I mean every, every time, and they have been many, there is a tiny (less than hair-width) sliver of light at the join, between the two ends, at the upper, thinner part of the wire. Nothing cures it and it is reducing me to screams of frustration. Soon I'll have filed it all away to dust. Any suggestions would be most gratefully received.