Akoya pearls

An akoya oyster is nucleated with a round bead cut from freshwater mussel shell, implanted into the reproductive organ along with a small piece of mantle tissue from a donor oyster. The donor tissue forms a pearl sac around the bead, the sac deposits nacre, and what comes out is a pearl with a round core and a round surface.

The donor oyster is not chosen at random. Technicians select it on nacre quality, luster and color, because the tissue that forms the sac carries those characteristics into the finished pearl. Two oysters in the same net, operated on the same day with beads from the same batch, can produce noticeably different overtones if the donor tissue came from different shells.

That is the whole reason akoya are so consistently round. The shape is built in from the start. It is also the method, developed in Japan a century ago and known as Mise-Nishikawa, that underlies every bead-nucleated pearl grown anywhere in the world today.

An akoya oyster is small and it usually carries one or two beads. A freshwater mussel carries dozens of pieces of tissue and produces dozens of pearls. That difference in yield is most of the difference in price between the two.

What you get for it is roundness and luster. Luster is the quantity and quality of light coming back off the surface, and on a fine akoya it is sharp enough to read as a mirror. The finest also show orient, a faint prismatic play of color as light refracts back through the nacre layers. Nothing else in pearls looks quite like it.

Freshly harvested akoya, before any processing, are called hama-age. Most farms do not sell them directly. They go to cooperative auctions, roughly sorted by size and quality and measured out by momme, the traditional Japanese weight unit still used in the trade, equal to 3.75 grams.

Buyers examine the lots under strong light and bid. The difficult part is that nothing has been processed yet, so what you are judging is not how the pearls look but how they will look after treatment. That takes experience and it is where a harvest is won or lost.

After auction the pearls go to processing factories. Nearly all akoya are processed, and that is not a compromise. A pearl out of the shell is not a finished pearl, in the same way an uncut stone is not a finished gem. Processing stabilizes it and brings out what it already has.

Maeshori, or pre-treatment, is the heart of it. It tightens the nacre and prepares the pearl for everything after. Bleaching with hydrogen peroxide cleans the surface and evens out body color, brightening pearls that came out cream or yellow. Pinking enhances the rose overtone that most buyers associate with the ideal akoya look. Then drilling, polishing and matching.

All of that genuinely improves a pearl. Tighter nacre and a cleaner surface send more light back, so a well processed pearl is more lustrous than the same pearl was coming out of the shell. What processing cannot do is add nacre that never grew. Time in the water sets the ceiling, and processing decides how close a pearl gets to it.

Pinking is the one step that adds rather than reveals, which is why the trade keeps a separate name for the pearls that skip it. There is a section on that below.

Matching is the labor-intensive part and the one that separates a good strand from an ordinary one. A technician sorts through thousands of pearls looking for consistency in size, shape, luster, overtone, body color and surface. The finest strands hold that consistency the whole way around and mirror from one side to the other.

Akoya color has two parts. Body color is the underlying color, usually white or cream. Overtone is the secondary color that sits over it: rose, silver, green or blue. Rose is what most people are chasing, and it is why pinking exists.

Natural-color akoya are the ones I chase hardest. Most people have never seen them, because they turn up scarcely and unpredictably. The blues, the silvers and the occasional gold are what experienced collectors ask for, and I keep people in Japan watching for them year round. We buy what surfaces, which means we never quite know when we will have more.

Natural blue akoya are a different thing entirely. They are untreated, they come out of the oyster that color, and no two are alike. The body color runs from pale silver-blue through steel to a deep peacock, with green, rose and lavender overtones moving across the surface. They are genuinely rare, they are usually baroque, and you will not find them in a jewelry store. We do not carry treated blue akoya.

They are also the one akoya color with a story worth telling on its own. How the color forms explains why they are almost always baroque, why no strand is ever uniform, and the single thing that separates a fine one from a poor one.

Akoya are never naturally black. A black akoya has been dyed or irradiated. That is fine as long as it is disclosed. Any seller offering black akoya without saying so is either misinformed or hoping you are.

On shape, most akoya are round or near-round because the bead is. Drop, oval and baroque occur less often, and fine baroque akoya with strong natural color have become far more appreciated in recent years.

Every harvest also produces keshi, meaning poppy seed. These form when the oyster rejects the bead but keeps the donor tissue, so the pearl that grows is solid nacre with no bead at all. They are usually small and irregular.

Akoya farms run along the southern coastline of Japan, from Mie through Shikoku and down into Kyushu, in protected bays with calm water, stable salinity and nutrient-rich currents. Most are family businesses several generations deep. Processing and matching happen largely in Kobe.

I have visited farms throughout Uwajima, Mie, Tsushima and Nagasaki and sat with the families who run them. What comes across is not the equipment or the technique. It is how attached these people are to the work, and how much of the outcome rests on judgment they have spent a lifetime building and cannot really hand to anyone else.

The oysters hang in baskets and nets beneath floating rafts. The bays are chosen carefully: freshwater running in from rivers feeds the plankton the oysters eat, but too much of it after heavy rain or a typhoon drops salinity to dangerous levels and the shells have to be moved deeper.

Red tide, akashio in Japanese, is the industry's oldest threat. An algae bloom can strip the oxygen out of a bay and kill a whole crop in days. Typhoons and warming water do the rest. Since 2018 the farms have also been losing enormous numbers of shells to what is called summer atrophy disease, tied to a previously unknown pathogen now identified as Pinctada birnavirus. It hits juvenile shells hardest, which means the losses compound from one season into the next.

China produced akoya at scale into the early 2000s and pushed global prices down hard. A series of destructive storms from 2007 wrecked much of that industry and it never recovered to previous levels. China still farms akoya in the south, but Japan dominates the fine end again. Vietnam produces a small volume.

Japanese production has been shrinking for decades, and not only because of the water. Costs are up, farms have closed, and the farmers and nucleation technicians are aging with too few people behind them. Nucleation in particular takes years to learn and there is a real shortage of people who can do it. At its peak the industry produced more than a hundred tons of pearls a year. In 2023 it produced about 13.2 tons, the lowest figure on record.

Fewer oysters means a smaller harvest, and a smaller harvest means the top of it gets spoken for early. That has changed how we buy. It is no longer enough to order against a description and wait for a shipment. We go, we look at what is on the table, and we take the strands worth taking. In a tight market, selection at the source is most of the job.