3.5 momme strand clasp

[pearlescence]

Hi All. We've just refurbished and re-strung a 3.5 momme type strand and this trademark was on the back of the clasp (which might be white gold and diamonds - not checked by me)
It's a very deeply impressed lozenge/diamond shape.
Anyone recognise it?

 

[AMc]

No I've never seen that mark before, but it will be fun to research and find out where it comes from!