Diamonds • Precious Gemstones • Jewelry • Gemology

Luster describes the quality or beauty of light reflected from the surface of the pearl. Sometimes it is expressed as the "glow". This luster is created by light simultaneously refracting from inside the pearls nacre and from the surface.

Of all factors used to judge pearl quality, luster is most important. Luster also has the greatest impact on pearl values.

The matchless beauty, size, and durability of the Australian South sea pearls are said to show a higher luster due to thicker layers and a unique formulation, aka quality, of the nacre secreted by the pinctada maxima.

Luster may be classified into the following grades.

Excellent - Fine
Finest quality nacre in greater thickness. High refraction & reflective qualities

Fine
Very good thick nacre but has less refraction & reflection

Commercial
Thin nacre. "Soapy" appearance caused by lower refraction & reflection