A very long time ago, I worked in the East Asian Studies Department at the University of Wisconsin, Madison, and my immediate boss was a lovely woman from India. I did many rolled hems on her 6-metre-long sarees. They were all beautiful silk and I used a 65/9 or a 70/10 needle and a 1 needle rolled hem with polyester thread. Now, when I sew on silk, I usually use a 65/9 or 70/10 Microtex Sharp (these were not available in the late 80s when I was doing this). I would also use silk thread because it is the thinnest of all the threads I have used, except for embroidery thread, which won't work in this instance. If you want that pico edge, I would first practice on some scraps left over from your tailor. I would first serge the two sides of the saree with the rolled hem matching the border color as closely as possible; then I would do the rolled hem on the two short sides, again matching the fabric as close as possible. I would then crochet the Pallu with thicker matching S-Lon Tex 210 Beading Cord or Griffin Silk Cord thread, matching the fabric once again to get the pico edge you want. Or you could finish the Pallu edge with the same rolled hem but with gold thread, and then find gold thread to match the sewing thread. I don't suggest you try doing the pico edge on your sewing machine, that will involve you using paper under the pressure foot and the silk, and then tearing it away, which can cause a ton of stress you don't want! I have done enough edgings this way, and it is not fun, and I would never try it on saree silk, not even dupioni! You might get the Pallu edge stiff enough if you can find some old-fashioned powdered starch, dissolve it totally in water and make it super thick so when you dip the end of the saree into it after hem stitching it, the saree border dries stiff as a board, you might be able to do it on a sewing machine, to me it wouldn't be worth it. If you don't know how to crochet a picot stitch, it is super easy, and you can learn by watching YouTube or getting a book from the library that has step-by-step pictures. It is super easy to learn. I would call beading stores in your area to find if they have the above beading cord or something similar, tell them it has to be silk or polyester and shiny, then take your spool of thread and fabric scrap and try and get a close match. Good luck, I hope you send a picture when you are finished, it will be lovely.