Akoya Pearl Nacre, Pearl Luster

How to determine the luster based on the pearl nacre. Chinese and Japanese Akoya Pearls

For the Mastoloni pearl experts. nacre and luster are the most important quality measures. Nacre quality is determined by analyzing layer thickness and layer density.  Both of these factors help us to determine luster.  Since the average consumer is not able to determine nacre quality, the most import factor for the consumer to understand is luster, which can be judged easily by the naked eye.

Pearls with high luster sharply reflect images around them, almost like a mirror.  They always display the characteristic depth, or three-dimensional glow, and a subtle display of different surface colors (orient) that is so prized among high-quality pearls. Pearls with low luster often look dull, chalky and lifeless.

Luster, in more scientific terms, is the reflection and refraction of light as it passes through the layers of aragonite platelet crystals that form a cultured pearl’s nacre. The intensity of luster is determined not only by the amount of these crystals but also by the specific geometric pattern in which they are secreted on the nucleus by the mollusk.

Many factors affect nacre secretion, determining the intensity of luster. The health of the oyster, the water temperature of the host environment and the level of nutrients available to the oyster all play a vital role in creating a pearl with superior luster.

Though the intensity of a pearl's luster can be an indicator of nacre thickness, and thus determine the durability of a pearl, this correlation is not always true. Some cultured pearls have very thick nacre combined with poor density resulting in mediocre luster.  This goes back to the formation patterns of aragonite platelets. Platelets in a very loose formation cannot refract and reflect light as well as very tightly packed platelets (nacre density). The loose formation phenomenon occurs more often in pearls grown in warm water.

Chinese Akoya Pearls vs Japanese Akoya Pearls

Chinese akoya pearls are cultivated in warm waters throughout the entire nacre growing period. This promotes quicker/more nacre coating, but the coating is often what many experts call “soft”, non-durable and typically lacking good luster.   The waters in which the Japanese oysters are farmed are much less polluted and subject to broader seasonal changes in water temperature.  Cold water slows down the nacre secretion process, reducing the size of aragonite platelets and producing tighter, more densely packed nacre layers. Japanese producers conduct their harvest only once a year in the freezing winter weather to ensure that the cold-water pearl coating is at its peak. Temperature combined with minimal pollution gives the fine quality Japanese akoya pearls their “mirror like” luster.

Are Akoya Pearls from Japan the Best Quality Available?

Given today's market, the answer is "Yes and No".  Lets explain!  Over the past 50 years, the world's weather patterns have been altered and economic conditions have changed.  Over the past decade, the total Japanese domestic pearl crop has been steadily declining to 70% less than what it was 15 years ago.  Shifting weather patterns and global pollution of the oceans affects the health of oysters and hinders their ability to produce fine pearls resulting in fewer fine pearls being available.  Labor costs in Japan, even in the most remote regions has been steadily rising.  These factors combined with major advances in Chinese pearl production capabilities, the termination of the Japanese pearl quality regulatory agency (JPEA) and other world economic factors, Japanese producers now buy large numbers of the absolute best quality Chinese akoya pearls and mix them with domestically grown products. Therefore, not all of the "best" quality akoya pearls are cultivated or originate from Japan, however the MOST ABUNDENT SUPPLY of the "best" quality akoya pearls can ONLY be found in Japan.

Wholesale Pearl Buying

Today, the wholesale Japanese pearl houses in Kobe are still the largest source of fine quality akoya pearls in the world.  This is a FACT.  Even today, these wholesale Japanese pearl houses are VERY SELECTIVE about their clients and ACCESS to their product is extremely LIMITED. The best quality pearls are only offered to companies like Mastoloni, which have spent generations forging trusted relationships. This explains why Mastoloni’s quality scales are higher than those of other companies.

The Fact Is....

Most pearls made available to the world markets DO NOT meet the minimum qualifications for Mastoloni's Japanese Akoya Graded Cultured Pearl Program. Depending on many factors (ie. weather & pollution levels) only 10 to 15% of the entire pearl crop may qualify for these high standards. At a minimum all pearl necklaces must be silver/white-rose color with 90-100% matching, 95-100% perfectly round, 90-100% free of "naked eye" surface blemishes, nacre thickness of at least 0.6mm, and moderate level of nacre density and good luster.

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