Hello, I’m new to this group and although I have some limited knowledge of how to identify pearls, I am not familiar with how to tell the different types of pearls. I purchased these earrings from a thrift store and I think they are dyed freshwater pearls, but I just wanted to make sure. They are set in 925 sterling marked 925 CP. They are gritty when rubbed together or on teeth. They are about 7.5 mm x 8.5 mm.