Help ID: French oval platter, crowned N with S and 54, iron-red

Hi all — hoping for help with a platter that's been in my family for years.

61.5 x 27 cm oval. Translucent hard-paste, good ring. Entire underside is unglazed biscuit, only the rim is glazed.

Iron-red stamp on the biscuit: closed crown over N, small S to the left, 54 to the right. Incised above it: "D - 47 - 9". No second mark anywhere.

Decoration is gilding only on white — ivy-leaf and interlace border, central lozenge medallion. Gilding is raised and the leaf veins look tooled.

The stamp is faded and scratches run across it rather than over fresh ink, so it seems to have aged with the piece.

Condition: one 2 cm chip with loss at the rim, general gilt wear, no cracks.

Is this a Sevres 1854 mark, or a Paris/Limoges factory using an imperial-style mark? Does the absence of a second mark rule out Sevres, or could the unglazed underside explain it? Any thoughts on the incised marks?

Thanks.

 

if you can post in the English language , you cal write your name in English as well.

or , should we just refer to you as Al ?