It's most likely made with the wire, probably softflex wire (which is the best IMO). You can also get some nylon coated stainless steel wire. The higher the strand count the better. The one I use to sting pearls is 7 strands and .30mm thin. I'm not really happy with it but it's the only one that I can find locally that's thin enough to go through pearl hole twice. The best coated stainless steel wire is 49 strands. It's the strongest. HTH.