I'm not an Oriental porcelain expert or anything, but the marks look Japanese to me. They bear a certain resemblance to 'dai nippon' marks which translate to Japan. Usually Chinese porcelain has four or more characters in their marks plus makers marks. Are there any other marks? I have concerns about the date 1792. It well may represent a design number rather than a date. It was not the usual thing to date the piece with European numerals during that era.
Also are the two opposite faces the same?
Just tidying up some blasts from the past (including some very ancient ones), largely for the benefit of anyone searching the site for information.
The 1792 date is of course spurious. This is a later copy of a piece actually from that date, originally produced in Delft in the Netherlands, as shown here:
That’s not a Delft mark though. The copy is from the Desvres pottery-making centre in France. If you Google for >Desvres double-sided salt cellar< you’ll see loads of examples with variations in decoration from multiple companies operating in that region, with a whole host of marks. Although I haven’t seen that particular mark, I’m almost certain it’s a pair of very stylised ‘F’ letters and for Fourmaintraux-Frères (Fourmaintraux Brothers) of Desvres.
I would think it’s probably from the first half of the 1900s, although it could conceivably be as old as the late 1800s.