I found you can also rub two of the pearls gently together. Fakes slide easily with no resistance. Non-fakes will slightly resist each other. I like this better than putting flea market stuff in my mouth. I think some old hollow filled glass fakes I bought on eBay might have passed the tooth test just because the glass was so scratched. But they were so old there was no question they were fake when I saw them in person. When you look down the drill hole, what exactly are you supposed to see if fake, if cultured, if natural? I've searched the forums but still can't quite figure this out.