Sterling Silver, Enamel and Opal Ring Arts & Crafts?

Looking to solve a bit of a mystery! This is a sterling silver ring, hand wrought, with royal blue, light blue and a mix of green and light blue enamels with a nice center opal (natural & not a doublet or triplet). No visible hallmarks, but looks like there's just a hint of one that's worn away with time. Note, there is no rhodium plating and it's not a more modern cast piece. Clues anyone? Thanks in advance!