Etienne, If you can be more specific, I can probably help you.What
type of trouble are you having with the cord - fraying, stretching or
breaking?Also, what are you currently using to string? Are you
combining stone,pearls and metal beads in one necklace? How long are
the necklaces? Etc…
I wouldn’t recommend Kevlar, as it would probably be too stiff,plus
it cuts itself. Some type of foxtail chain may work.It’s used a lot
in heavy Squash blossom necklaces and doesn’t stretch or break.
Feel free to e mail me @ @Susan_Hoge, or post details
about necklaces here so I can help you.