Baby Nurse, your last photo catches the iridescence beautifully.
I restrung my near round Tahitians, replacing a silver pearl with a dark peacock pearl. The difference is subtle but I like it.
Twice already I've had to restring it because the Beaders Secret was slipping out of the knot on the ball end of the clasp. The ball clasp is so much like the end pearl in size and shape that I tend to grab the wrong thing when unclasping it. This eventually stretched out the thread, but only on that side! The dab of glue I used on the knot this time should solve it.