Vintage Signed Donald Stannard White Enamel & Gold Tone Clip On Earrings Chunky

Vintage Signed Donald Stannard White Enamel & Gold Tone Clip On Earrings Chunky There is white enamel missing from one of the earrings, maybe it didn't get enamel on that part?? I would think it would be hard to chip off baked on enamel. See Photos as they are part of my description.