My grandfather collected many Chinese stamps in his lifetime. When he passed away, his primary collection was sold at auction.
When we were cleaning the house that he lived in, we found a box, filled with nearly 1,900 Chinese Imperial Post Stamps, all with the Chinese Imperial Post Overprint. They are not worth much individually: only a couple of dollars each. But together, they are something that our family needs to sell.
However, we know that he did have some forgeries in his collection that he marked as such. These stamp were not marked, but they could be forgeries anyway. I don't want to sell them to others if they aren't genuine. The stamps would have been passed over, real or fake, because they were outside of the focus and value range of the collection.
I know that with coins, relatively experienced collectors can identify most fakes from photographs. I am not sure if the same applies to stamps, but if anyone can tell if they are genuine or not, it would be greatly appreciated.