Lost My Favourite Ring

I managed to lose my favourite ring today while having lunch out with three friends. I was hoping the ring had simply slipped off my finger when I was rummaging through my bag (as that has happened with another ring before), but I've seen no sign of it. I called the restaurant to ask them to keep an eye out for it. However, I have a feeling that it's long gone. :-( What's really infuriating is that I only had it for a month. It was this beautiful Celtic ring that I picked up at the British Isles Show and I just loved it.