Can you take another set of photos on a neutral background such as a white or light colored sheet?
Lay a ruler down next to the piece. Shoot the front, back and sides, if possible. A macro shot of the hole would be nice, too.
I'd like to know what the surface looks like, as well.
Does it look like ceramic glaze or is ir a patina of some sort?
I'm looking to see if there are any clues as to manufactuer process or age.
Was the object cleaned after it was picked up or did it come out of the surf that way?
An object that was fairly clean would indicate a newly dropped piece as opposed to ne that sat in ocean water for many years.
Does the surface coating/treatment continue into the hole?
This would give us some clue as to the manufacturing process.
Are those chip marks around the hole? Are there any sharp edges to those chip marks or have they been softened by the coating treatment?
This would help us to figure out if the hole was made during manufacturing or after
Are there any markings on the back?
A marking such as "Made in China" or "Hecho enMexico" would help detrmine the date and origin of the piece.
Ian