• Don’t look at pearls under strong direct light. Go for fluorescent instead.
• A prism of colors within the pearl is called orient.
• Jewelers rate pearls luster from high to low.

Simply put, luster is the deep inner glow that emanates from a well formed, thick nacre. If you observe enough pearls, you will soon be able to tell the difference between luster and shine. Shine is a surface quality frequently mistaken for luster, but don’t be fooled. Here’s a few tips to help tell the difference.

1. Luster is rated from high to low. High luster pearls will appear iridescent, while low luster will seem hazy and dull.

2. Holding a pearl under fluorescent light, you should be able to detect a marked difference between the bright area where the light hits the surface and what is called the "ball" of shaded area. This contrast is caused by thick, well formed nacre and gives the pearl its glow.

3. Roll the pearls around to make sure that the luster is uniform throughout.

Orient is an iridescent quality that is rarely found in round pearls. This amazing effect occurs mostly in baroque gems with very thick nacre and is basically a prismatic display of all the colors of the spectrum shining from deep within the pearls skin. This is probably the biggest difference between natural and cultured pearls because natural pearls are all nacre and cultured have the large mother or pearl nucleus. The thicker the nacre, the more likely you will see this glorious display of color.

Answer to quiz: c