Vintage Sterling Silver Blood Agate Clip On Earrings

Cute tear drop shaped sterling silver earrings with clip on backings. I believe these are possibly blood agate or another form of agate. They're stamped sterling on the backs, but there is some greening on the hinged ear lobe part, so I think that only the metal setting is actually sterling and not all of the metal. I've cleaned them really well and removed all the greening I could, but it will come back. If I were keeping these I'd convert them to post earrings by clipping off the clip on portion and gluing a sterling post on. There's no greening on the actual earring or tear drop shape, so modernizing these should resolve that problem. I picked these cuties up from an antique mall out in New Mexico on my travels, so they're likely Native American or Mexican made, but have no markings for a maker. They're a little over 1/2" tall and about 1/3" wide. Stones and settings are in excellent shape!