Here's what I do:
Cut a length of thread 5 times the anticipated final length of the knotted strand.
Double the thread and make a large knot, then string on the first 3 pearls in reverse order.
Thread on a bit of gimp, then pass the needle through the clasp and back through the end pearl. Snug up the thread + gimp + clasp carefully.
Make an overhand knot with the thread around the existing thread between the end pearl and the next pearl. To seat the knot, pull the two threads apart firmly.
Pass the needle through the next pearl, knot, then the 3rd pearl and knot.
Trim off the original knot.
Keep going, knotting between each pearl until you get to the last 4 pearls from the other end-- just pass the needle through all 4 of them without knotting in between.
Thread on gimp, then the other end of the clasp, then pass the needle back through the end pearl. Snug up the thread, then knot between the end pearl and second pearl.
Pass the needle back through the 2nd pearl from the end, make a knot, then repeat with the 3rd pearl, then knot, and finally trim off the thread. Be sure you cut the right thread!
2 suggestions:
Practice -- get your technique down-- by making a mini strand 10 pearls long. When you can do that the way you like it, cut it apart and make the real strand.
Some people use a darning needle or an awl to help guide the knot to the correct position before tightening it.
I use tweezers, whose edges I have filed down so they aren't sharp and don't cut the thread.
Others don't need any tools! Find what works for you.
