Cubic zirconia looks like diamond and, in many respects, performs like it optically, but it's considerably heavier. Density is one of the few physical properties that gives the materials away as different things.
Built For Ease
For a pair of earrings to sit and hang the way they were designed to, the clutch back placement matters. Close to the lobe produces a flat, snug result; more post exposed creates a small gap that changes the forward angle.
Elemental Detail
Earring posts are made in the same metal as the earring, yellow gold, white gold, rose gold, sterling silver, or platinu. For sensitive ears, platinum and high-karat gold posts are the preferred specifications because their high purity minimizes reactivity at the piercing.