Antique Silver Cigarette Case

This is a recent buy, I love the art and craft look to it. The Hallmarks at the back seem to suggest that it was imported to London, the problem is the import mark seems to be upside down so I might be wrong. As you can see it has a few dents and scratches but to me it doesn’t detract from simple lines. The case opens as a purse with a blue cabuchon stone, I’ve tested the stone thinking it could be a shappire but it didn’t register as that, it’s definitely some type of stone. Unfortunately it doesn’t have a makers mark but somebody might have a clue to the maker.

Many thanks for looking