Omega back earrings in solid 14K yellow gold.
What an omega back is. A hinged clip shaped like the Greek letter omega that folds up behind the lobe. It grips far more securely than a friction butterfly back, and it takes the weight of a heavier earring without the lobe drooping.
Pierced and non-pierced. Most omega fittings run a post through the piercing and then clip; some are clip-only and need no piercing at all. The product page says which.
Styles here. Hoops, polished ovals and stone-set designs including turquoise.
Why it matters. If you have ever lost an earring, the back was almost certainly the reason. An omega clip is the answer for anything you would be upset to lose.
See also omega clip earrings, non-pierced earrings and all Yellow Gold Earrings.