Luster

This is the quality of the light reflections from the pearl's surface. Pearls are said to have high, or very high, luster when the reflections are bright and sharp. When the light reflections are weak and fuzzy (or diffused), the pearls are described as dull. The Tahiti Cultured Pearl rivals anything grown in Japan for the sharpness and intensity of reflected light from a pearl's surface. In fact, pearls from French Polynesia often possess such a mirror-like finish and radiant brilliance that their overall appearance is likened to that of very shiny metallic objects, such as ball bearings.

The only problem with such an analogy is that it suggests a cold, steely beauty. In reality, lustrous Tahiti Cultured Pearls have warmth to them--even when their surfaces gleam as brightly as a dress shoe.
Regardless, the lustre of the Tahiti Cultured Pearls is just like their colour--all natural.