Wow, many thanks to all of you.
I guess I underestimated the complexity of speaker cables purity issue. And underestimated the kindness and patience of your folks.
It took me a while to do further research and I do get it a little nowadays (...finally) that gauge awg are american measures of cables, and that for an average amplifier of mine of 100 watt, (with medium sized speakers) probably a 12 awg would give best quality.
I do understand its better to have oxygen free copper rather than copper, and have skipped my silver wire idea. I will go with OFC.
I also understand in principe that many wire geometries, wire treatments, breaded etc have more effect - but due to complexity and my beginner understanding I'd leave the wire geometries and structures apart.
Once again thank you all.