Maker's Mark unidentified // silver children's cup

I need your help!

I am looking to identify a French (Circa 1918 or earlier) MAKER’S MARK.
the mark looks like this :
a diamond shape laying on it’s side.
and inside is a J then a double headed “thing” and then a B.
the “thing” looks like a legless ant or a raised figure 8.

if anyone can identify it for me please let me know.
the silver cup is a 95% large guarantee, so I think it’s a better quality maker.