Pearl Cultivation Process | Tensei Pearl

Typical timing: from around October

Fine pearls are born from fine mother oysters. We select the mother oysters that will receive a nucleus and the donor oysters with excellent genes.

In the Shimonada area where we farm, Akoya oyster spat are collected alongside pearl cultivation. Together with the neighboring town of Ainan, the area accounts for most of Japan's pearl mother oyster farming.

Typical timing: around April to July

Nucleus insertion is the first and last step in which people directly touch the inside of the mother oyster. That makes it the most important step, where the craftsman's skill comes into play. A nucleus, made by rounding the shell of a freshwater mussel, and tissue from a donor oyster are placed in the right position inside the mother oyster. Like people, no two mother oysters are exactly alike.

Grasping each oyster's character in an instant, the craftsman relies on the feel of the fingertips and experience to cut the insertion point with a scalpel through the narrow opening of the shell, and inserts the nucleus quickly, accurately and without stressing the oyster.

Needless to say, this work directly affects the quality of the pearl, but it also greatly affects how many oysters survive and how efficiently the work goes.

One person inserts nuclei into about 600 mother oysters a day.

Typical timing: from around July

After letting the oysters rest well for about a month, we move them into tall nets and take them offshore to places rich in plankton, their food, to encourage the nacre to form.

A good fishing ground needs depth, protection from sudden changes in water temperature, currents rich in plankton, and minerals washed down from the mountains by rain. But fishing grounds change every year, and they are also affected by air temperature, water temperature and rainfall.

Typical timing: from around July

An oyster that has received a nucleus cannot be operated on again. After moving out to sea, all we can do is trust the oyster's own life force.

Managing the fishing ground means creating an environment where the oysters can live comfortably. Plenty of plankton also makes other creatures active, so barnacles and seaweed attach to the oysters.

Cleaning them off regularly keeps the oysters healthy. We clean the oysters regularly with a work boat called a washer boat.

Special equipment on board uses water pressure to remove dirt from the oysters. This has two purposes: cleaning them, and giving the oysters moderate stimulation to make them more active and thicken the nacre.

When the dirt is especially bad, we clean the oysters one by one by hand. This patient work keeps the oysters healthy and nurtures fine pearls.

Typical timing: late December of the following year to early January

When snow begins to fall on Yura Peninsula, after about two years, pearls with well-layered nacre are ready.

When the water temperature falls to around 16°C and the oysters store nutrients in their bodies, they begin to secrete a finer layer of nacre. This is called "keshō-maki" (the finishing coat), an extremely important final stage in pearl formation.

Judging that timing can only come from many years of experience; it is the essence of the pearl craftsman's art. If the harvest timing is wrong, the luster of the finished pearls differs greatly.

Japan's four seasons nurture the mystery of life, and beautiful pearls are born.

The harvested oysters are separated into flesh and the adductor muscle. The flesh containing the pearls goes into a crusher, and the pearls are taken out.

When the crusher breaks up the flesh, the pearls fall to the bottom of the machine. A polishing machine then rubs the pearls against each other to remove dirt from their surface.

After that, the moisture is removed in a special dryer, and we have "kidama": pearls that have not been processed at all.