Mystery FJ maker's mark on arts and crafts style letter opener

[Peartree]

Hi,

If you recognise this makers monogram (FJ) I would love to hear your thoughts, thank you. As you can see it's on a remarkable letter opener, very high quality, with cloisonne enamel handle. It is marked STERLING, so I thing American and probably c 1910-20, but perhaps it is more modern. 19.5 cm long.

Thank you.

Anthony

[Aguest]

:::::: The way the [STERLING] hallmark is stamped makes me think about Australia or New Zealand. :::::
::::::::::::::::::::::::::: Hallmark looks familiar, though, will try to remember :::::::::::::::::::::::::::::::

[Peartree]

Thank you