My PSA for the week...The absolute best fret cord is a product called "STRINGTH". Do a search on google and you'll find it. I believe the #5 is the proper thickness. The gold color goes well with Mangla teaks.
I have used stringth. It is an excellent cord. No. 5 is best for sitar frets. Nice variety of colors also. Has a tendency to lose its sheen/luster very quickly and superficially frays a bit. Greetings, D'esouz