Unknown Mark on Amethyst Ring

[Ninotchka]

I was given this ring as a gift about 10 years ago from someone who got it at an antique store. I don't know anything else about it, so I've been trying to do some research to try and find out who made it and about how old it is. I apologize for the quality of the picture of the marks. The upper left mark looks like a plus sign and the one right next to it is a dot. Underneath those two is just a vertical line. Any help at all would be very greatly appreciated! Thanks in advance!