Antique Japanese Sterling Silver Satsuma Belt Buckle - mid 1800s

This elegant, and finely made, buckle has only one mark to identify it. It is on the reverse, just above the hook. To my ageing eyes, it looks like the makers marks used by gold and silver smiths, throughout the history of the craft, before modern laws began to call for uniform markings. What else may be contained in that mark, I cannot ascertain. This is a very old piece, however, with no signs of corrosion or wearing out of a plating. I am confident in my conclusion that it is Sterling. Please realize, however, that this is all that I have to offer, by way of assurance. Please use your own judgment. Thank you!