Collection: Pearls | The Jewel Box

Q: What is an Akoya pearl?

It is a cultured pearl grown in the oyster Pinctada fucata. GIA reports that Akoya pearls average between 6 and 8 millimetres, and pearls above 10 millimetres are rare.

The luminous world of pearls, from the Japanese Akoya tradition to the forms and settings treasured across generations.

A pearl made by patience

Kokichi Mikimoto was born on 25 January 1858 in Toba, on the Shima peninsula, to a family that ran a noodle shop. Natural pearls from the waters of Ise were growing scarce, and he decided that if the sea would not give them freely, he would persuade it to give them on request. The road was not smooth: money ran short, the public doubted him, and red algae damaged his Akoya oyster beds before he succeeded, on the island that now carries his name.

In 1893 he cultured a semi-spherical pearl. By 1899 he had opened a pearl jewellery shop in Ginza, and in 1906 it moved to Ginza 4-chome, where it has remained. He died in September 1954, having turned an idea that sceptics dismissed into an industry.

A Japanese pearl therefore comes with a story of method as well as a story of place, and the strands in this collection are read in that light: the nacre, the lustre and the matching first, then the clasp, the knotting and the box that has travelled with them.

How a strand is judged

The Gemological Institute of America names seven factors in the value of a pearl: size, shape, colour, lustre, surface quality, nacre quality and, for strands and pairs, matching. Of these, lustre is the one to learn first. It is the brightness and sharpness of the reflections on the surface, and GIA calls it possibly the most important factor of all. Hold a strand near a window and look at the reflection of the frame: on a fine pearl its outline is crisp, and on a dull one it blurs into a glow.

Akoya pearls come from the oyster Pinctada fucata and, by GIA's account, average between 6 and 8 millimetres, with anything above 10 millimetres considered rare. Nacre matters because it is what the pearl is made of. Where it is thin, a visible nucleus or a chalky look weakens both the lustre and the life of the pearl.

Matching is the quiet factor. In a good strand the pearls agree in size, shape, colour and surface so closely that the eye reads one object rather than a count of many. Where they do not, the maker has usually done it on purpose, and the piece will say so.

Reading a Japanese certificate

Japan has its own tradition of pearl reports. A certificate is a laboratory's statement about a pearl, which may include an X-ray to show whether it is nucleated, and Japanese Akoya are also graded under names such as Tenyo, Hanadama and Rosé, according to nacre thickness, surface smoothness and lustre. Two laboratories are well known in this field, the Pearl Science Laboratory and the Pearl Institute.

Read these documents as evidence rather than verdicts. One Japanese dealer notes that the criteria for passing are somewhat obscure, that results can differ between testers and that a graded strand is not always more beautiful than an ungraded one. GIA has since added a five-range nacre scale to its pearl reports, introduced in 2025. A certificate is most useful when it matches the strand in front of you, pearl by pearl, and is kept with it.

Keeping a strand for a lifetime

A pearl is soft and organic, and wears the habits of its owner. Put it on after perfume and cosmetics, wipe it with a soft cloth when it comes off, and store it flat in a pouch away from harder jewellery. GIA's advice is to have strands inspected regularly and restrung when they show wear, because the string can fail before the pearls do; a knot between each pearl keeps a broken strand from scattering.

Every strand in this collection is examined and documented in Tokyo before dispatch, with its clasp, knotting, lustre and any certificate described in plain terms.

Looking for a strand of a particular size, colour or maker?

Our Otoriyose private request desk can look within Japan for a specific pearl necklace or pair and reply with what is available.

Go deeper

The Jewel Box: Japan's jewellery almanac, where pearls are the first movement
Mikimoto and the Akoya: a collector's guide to Japanese pearls
Pearls Explained: Akoya, South Sea, Tahitian and freshwater, and how each is graded
Kept in the Box: how Japan stores and cares for jewellery and watches
Jewellery: the whole shelf, by house, material and form
Authenticity and Condition: how a piece is examined, graded and documented

Frequently Asked Questions

What is an Akoya pearl?

It is a cultured pearl grown in the oyster Pinctada fucata. GIA reports that Akoya pearls average between 6 and 8 millimetres, and pearls above 10 millimetres are rare.

Who was Kokichi Mikimoto?

He was born in Toba in 1858 and cultured his first semi-spherical pearl in 1893. He opened a pearl jewellery shop in Ginza as early as 1899 and died in September 1954.

What does Hanadama mean?

It is a grade name used for Japanese Akoya, alongside Tenyo and Rosé, and it is assigned by laboratories according to nacre thickness, surface smoothness and lustre. The exact criteria are not published uniformly, so treat the certificate as one piece of evidence.

Which factors decide the value of a pearl?

GIA lists seven: size, shape, colour, lustre, surface quality, nacre quality and matching. Lustre is usually the first to learn, because it shows the brightness and sharpness of the reflections on the surface.

How often should a pearl strand be restrung?

GIA advises regular inspection and restringing when the strand shows wear, because the string can fail before the pearls do. A knot between each pearl limits the damage if it breaks.