I have owned these 1 1/2" sterling malachite (?) and another brown stone earrings for some time. Sterling I bought from the same person was marked Los Castillo, so I thought this mark might be of some note. I have looked in MEXICAN JEWELRY by Davis and Pack with no luck. Could someone with more knowledge or literature than I have help identify the mark? Thanks.
They are marked 925. The mark is a large M with what I think are a small G and small H. Then TG-14 (or TG-14).