Vintage MMA retailer TBM Gold Tone Drop Earrings

Product Name: Vintage MMA retailer TBM Gold Tone Drop Earrings
Late 1980's reproduction of Roman/First Century AD jewelry purchased at Metropolitan Museum of Art. MMA TBM (The Brooklyn Museum) USA is signed on the back of both. These need to be cleaned; I do not know how to properly do that so the new owner can. Gold spheres or orbs open at the back and attached to small discs with four tiny granules at the intersection of the body and the earwire. They are gold in retailer color but not sure of the purity. I have seen these identified as Sterling silver with a heavy 18K gold overlay. But I have not had these looked at by a professional. Difficult to tell what will clean off or what may be surface wear due to age. Good vintage condition overall.