Need help with unusual design gold pin

[tominhope]

frontbackdesign

[gauntlettgems]

Looks celtic like maybe a kilt pin. 

[old.crows.nest]

I agree with gauntlettgems, Celtic design.

Also want to add, your brooch is styled after a Penannular Brooch.

https://en.m.wikipedia.org/wiki/Celtic_brooch

[old.crows.nest]

Have you research the other Hallmarks on your brooch? I think I see the Hibernia mark for Dublin, Ireland but cannot make out the date letter.

[tominhope]

They are hard to read. I think I need a loupe.

[debora_34_]

Doesn't look Scottish and not sturdy enough for a kilt.  Try "Irish cloak pin."

Debora

[ginarae]

Yes, looks like Irish tourist jewelry..pretty!