Yes Zeide,
After 2 minutes of rubbing on the strand, I realized this wasn't nearly as easy as doing a ring. Since they were showing some improvement, I'd already decided to try the salt slurry. They are in the rinse water now. Since we are on a well, there is no chlorine in our water but who knows what minerals. So I buy water to rinse them in. I'd already tried this on some eBay "learning pearls" and liked the results. I wasn't worried about damaging them; I had gotten them to cut in half, drop on glass to see how high they bouced (some test I read about), and in general play with. The cultured pearls I have rinsing now were my mother-in-law's so I'm guessing 1940-1950's, 6-7mm. She was a smoker. I don't think that does good things to pearls. The eBay ring I first tried the sunshine cloth on is old. The shank (the back side on the ring) is thin like it's been worn a long time. I think the pearl is South Seas but I'm too inexperienced to know for sure.
I guess if the point of this thread is to make a guide, we need to put a warning on these more extreme treaments.