Pearl Grading: Luster (Lustre)
Pearl Grading System
Pearl grading is very similar to the "4 C's" of diamond grading in that the pearl grading system takes into consideration several key categories of qualitative comparison analysis. The pearl grading system consists of five main categories:
1. Luster (Lustre)
A pearl's "luster" is one of its most important physical attributes, and the highest determining factor in grading and valuation after its regional origin. A highly 'lustrous' baroque pearl is probably more desirable than a perfectly round pearl with an opaque, or "milky" surface lustre. The quality and depth of a pearl's nacre gives the "lustrous" quality for which pearls are valued. To explain it simply, luster refers to how "shiny" or "dull" a pearls is:
- Low lustre: Pearls surface appears "chalky" and/or "milky."
- High lustre: Pearl surface reflects light and shows mirror-like reflections.
To evaluate a pearl's luster, place your pearls on a white piece of paper or white cloth near a window on a bright and sunny day, but do not place the pearls in direct sunlight. See how the pearls reflect the shape of the window frame. The clearer and more sharply defined the window's reflection, the more lustrous the pearl.
A Pearl's luster will be dependent on the quality of care given to the oyster in its early growing stages, as well as its incubation period - typically three to five years. The better the pearl producer cares for the health of his molluscs, the higher the pearl quality produced by those happy molluscs.
With "natural" and cultivated pearls, higher-quality 'lustrous pearls' make up only a small fraction of the pearls available on the market, and they will command very high prices.
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