I bought 40 vials of them from a reputable source 6 yrs ago, it did not come with any kind of authentication but however I did have 5 out of the 40 acid tested a few years ago, the outcome was that with the 14k gold acid they dissolved quickly and with the 10k acid it didn't dissolve all the way so I believe it might be about 8k gold or so but I'm not sure. These are real gold flakes and if you don't believe me go get it tested I'm not asking that much for these and I you can look at one of my positive feedbacks, someone that received 5 vials from me stated that the onse he got were the best flakes he had seen from listia! Some vials might be more gold then others I don't know and I didn't want to test every vial. If you think about it these flakes are very light in wieght so your not going to get rich off of these and they are more for fun and make for a cool conversation peace!