Antique Victorian Era Hand Painted Oyster Plate

This isn't a 20th-century reproduction! It's unmarked, but there should be no doubt about its age. Despite being 9.25 "wide, it weighs just over 13 oz. Unfortunately, there is slight damage on its edge; otherwise, this would be valued at $300-$400. See photos.  

9.25" Diameter 

13 oz.