Plus-sign inside a circle

by Paulette
(Picayune MS)

Hello: I was given what appears to be a vintage amethyst ring in a rose-gold setting; hallmark inside looks like a cross or plus-sign inside a circle. There is a deeply engraved tulip design on each side of and below the oval stone setting. Style looks European (spouse's ancestors were from Germany and Ireland, if that helps). Can provide a photo if you'd like to see it. Thank you! Paulette