My brother bought this from a European antique dealer in the 80's. The dealer bought it in the 60's in England. Any help identifying the mark and plate would be appreciated. The mark is under-glazed, incised, and very difficult to see. We both tried to enhance it and came up with different marks for the lower right-hand corner. I have attached the original mark + the 3 enhanced marks as well as the front of the plate. Thanks for any and all help. We both believe it is Qing dynasty, probably around the late 1800's or early 1900's, but we're trying to narrow it down as close as possible for insurance purposes.