A pearl without luster is hardly a pearl at all. In fact, a pearl’s true beauty is often determined by its luster; the inner glow that appears to illuminate from the center of a high-quality pearl.
Pearls with a very high luster generally share the same characteristics including sharp and strong reflections to light and a good contrast between a pearl’s dark and bright areas.
A pearl's luster can be weak or strong depending upon a number of different factors including the following:
Shape affects a pearl’s value as follows: Round and near-round pearls are considered the most valuable because of their rarity. The fact is that irregularly shaped pearls are more common in nature than perfectly round pearls. In an attempt to create round-shaped pearls, pearl farmers use large, spherical nuclei to increase their chances of culturing a rounder pearl.
Actually, pearls need love! The more you wear them, the more they like it. Your body’s natural oils help keeps pearls lustrous. There are things, however, that pearls aren’t too fond of, including household chemicals, perfumes, and the chemicals often found in hairspray and makeup. The very best way to preserve your pearls is to wipe them with a soft cloth and keep them stored separately from your other jewelry to avoid surface scratching.