Vase transformed into a lamp

I suspect this is not an authentic Delft vase, the marks are either missing or hardly visible. Besides, the metal base has been glued to the vase, partly covering the ceramic surface.
I'd like to know what can indicate that this is not Delft: shape, the state of the glazing (no crazing, but scratches and bits missing), ornament ?
If it's authentic, then what period could it be?
Thank you very much, would really appreciate your response.