Guinea Bissau Pearl Ruby Bridal 2014 Fashion Gold Jewelry 41

Guinea Bissau Pearl Ruby Bridal Fashion Gold Jewelry. 

By Aamir Mannan.

High-lustre pearls are bright, and have a deep-seated glow. They reflect objects near them clearly. Though high-lustre pearls usually have a thick nacre coating, thick nacre doesn't always guarantee a pearl will have high lustre. This is true because genetic imperfections in some oysters don't allow them to secrete nacre in perfect patterns that result in high lustre. Low-lustre pearls, on the other hand, have low reflective and refractive qualities. They may appear too white, or dull or chalky, and they usually have only marginal nacre thickness.

Lustre of Akoya pearls

Many experts believe that Akoya pearls have the highest lustre of all cultured pearls, and it has to do with their nacre coating. The Japanese waters in which Akoya pearls grow are considerably cooler -- 10 to 15 degrees cooler -- than those in warmer climates, where other types of saltwater cultured pearls are grown. The cooler conditions cause Akoya pearls to develop their nacre coating more slowly, and with a more compact crystal structure. This is what increases Akoya pearls' reflective and refractive qualities. Even though Akoya pearls' nacre coating is generally thinner than that of most other saltwater varieties -- about a half millimeter thick -- their lustre shines the brightest.