My experience in buying plum and black cherry seeds from Chinese sellers on eBay!
I bought black cherry seeds and bonsai plum seeds that sellers from China were selling on eBay. They looked like this(both black cherry and plum seeds came in a small ziplock bag and the seeds looked like this.) This is what the seed inside the pit looked like. I used the same method of growing these fruit seeds like I did for my other fruit trees by germinating them in the fridge first and taking the skins off of them when the skins became soft enough. I then planted the seeds in soil maybe 3-4 weeks later. When I tried to look for them in the soil to see if any germination had happened, they had DISAPPEARED. I believe the seeds were FAKE and so they just dissolved in the soil which is why I couldn't find them. So now I will not buy seeds from Chinese sellers on eBay anymore. It is so much better to buy seeds from the grocery store and if you decide to buy online, buy from American, Canadian, and South American sellers on eBay who sell fruit seeds...