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Pearl Cultivation Chronicles: Balancing Size and Quality in Akoya Oysters

Today, I departed for a pearl cultivation farm to harvest pearls. The journey started with a 2.5-hour Shinkansen ride from the nearest station to the company, taking me to Hakata. From Hakata, it’s a 10-minute subway ride to Fukuoka Airport, and then a 30-minute flight from Hakata Airport to the island where the pearl cultivation farm is located.

The pearl harvesting operation began on December 7th. After four days of continuous work, the harvest has been temporarily halted due to persistent rainy weather. Currently, I’m waiting for the sorting of the pearls collected over these four days.

The daily harvest includes approximately 30,000 to 40,000 shells. So far, around 40,000 shells (The net weight of harvested pearls is over 50 kilograms.) of pearls have been harvested. As for the quality of this season’s pearls, the latest reports indicate, “The larger sizes were not particularly good, but the medium sizes are decent.”

The “larger sizes” refer to lots using 2.5bu nuclei, equivalent to 7.57mm in size when converted. If Akoya oysters are implanted with a 7.57mm nucleus, it should ideally result in pearls larger than 8mm. However, according to the farm director, pearls cultivated aiming for 8mm using these oysters did not yield satisfactory results. Specifically, there is a higher proportion of pearls with protrusions rather than round pearls.

It is crucial to insert nuclei of appropriate sizes for Akoya oysters to match their dimensions. However, the farm’s desire to produce larger pearls conflicts with the goal of creating beautiful pearls. Pearls are a matter of weight in the market.

The decision between:

  1. Taking safety measures to cultivate smaller pearls for a more beautiful appearance, increasing unit price by maintaining higher quality.
  2. Prioritizing the total weight of produced pearls, sacrificing some quality by inserting larger nuclei into Akoya oysters. This may slightly reduce the unit price, but overall, it increases total pearl weight, leading to higher revenue.

The choice between 1 and 2 depends on the stock of Akoya oysters at the farm and the values of the farm director. The company I belong to owns two pearl cultivation farms, each with distinct characteristics.

One farm is located in an area with abundant oyster feed (chlorophyll, oxygen concentration, plankton) and experiences significant seawater inflow due to its location in a Rias-type coastal area, despite being nestled within a bay. This high seawater inflow means ample feed for Akoya oysters. Oysters at this farm tend to grow faster, providing an advantage in cultivating larger pearls (8mm and above). However, due to the active nature of the oysters in such a nutrient-rich environment, there is a slight disadvantage in forming the smooth surface characteristic of large pearls.

The second farm, with the opposite characteristics, is situated deep in the back of a Rias-type coastal area, resulting in less seawater inflow from the open sea. Consequently, the plankton, a source of food for Akoya oysters, is limited. Oysters in this region grow more slowly, and achieving the necessary size for successful pearl cultivation (using 6.3mm nuclei for 2.1 sizes) is challenging. While this may pose a disadvantage in a pearl business that relies on weight, the slow activity of the oysters in this area tends to produce pearls with an exceptionally delicate and smooth surface.

Despite numerous challenges, this second farm has consistently produced top-quality pearls. It has won the title of Japan’s best pearl four times in the last ten years, even amidst difficulties such as poor oyster growth due to environmental changes. In the recent auction limited to pearls harvested in the 2023 fiscal year, this farm secured the highest bidding price.

Returning to the main topic, the pearls harvested from oysters specifically cultivated for an 8mm size weren’t of high quality. However, pearls harvested from oysters implanted with 2.3mm nuclei afterward were reasonably good. The nuance of “reasonably good” in Japanese might differ from English; in the context of a test scored out of 100, “reasonably good” might be around 73.

These harvested oysters are cultivated for over a year, with the nuclei inserted from June to December 2022. At this point, the harvest seems to have concluded from June to September. Starting tomorrow, the farm director and I will begin sorting the harvested pearls.

I’ve been in this line of work for about 9 to 10 years. Over the years, many people have expressed a desire to visit a pearl cultivation farm or see freshly harvested pearls, but such visits are not permitted for employees, let alone everyone. These activities are crucial for the company’s revenue, and hence, not everyone is allowed. Despite this, I feel fortunate that I can participate in the sorting of freshly harvested pearls every year. This sense of happiness is relatively recent for me. In the initial three years, lacking knowledge and experience about pearls, I often found myself unsure about how to sort them. As a result, I would occasionally doze off during the sorting process. However, around the fourth year, it suddenly clicked, and I comprehended all aspects of pearl sorting, including the methods and intentions. The experiences of the first three years seemed to awaken suddenly.

Since then, my hands move instinctively when sorting pearls. It’s like eating rice with chopsticks without consciously thinking about picking up each grain. In just a few seconds, when gazing at a batch of pearls, my hands naturally start sorting them into high and low-quality categories. Simultaneously, freshly harvested pearls appear mystical and irreplaceable, much like newborn babies.


With that, I’ll conclude this article. I’ve tried to keep it well-organized, but my writing tends to deviate as I go along. Thank you to those who have read this. By the way, I wrote this article while on the Shinkansen from the company’s nearest station, taking approximately one and a half hours.



I am part of a Japanese company with an Akoya pearl farm. Apart from the company, I personally run an Akoya pearl shop. I would appreciate it if I could share smiles with various people through pearls.

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