Gem Focus November 2021: Keshi Pearls

Posted on November 16, 2021 by Çiğdem Lüle, PhD, FGA, GIA GG, DGA

Keshi; more than tiny poppy seeds in the pearl business…

Human’s love and affection for pearls go back thousands of years, especially in the Eastern world where they were considered a divine gem. Natural pearls were so rare that they were only owned by royalties, even the tiny ones were utilized both in jewelry and on clothing.

Keshi means “poppy seed” in Japanese and is used to refer to very small items. The term was first used in context by the Japanese pearl farmers to describe the tiny pearls found in cultured oysters. Later, these undesirable pearls became popular in the 1980s and sold in a separate category.  Although small, their superior luster and baroque shapes proved to be desirable. Keshi occurs as an accidental byproduct of the culturing process. The exact cause of keshi is not fully understood. However, experts believe that the likely cause is that the mussel rejects and expels the implanted bead nucleus but the mantle tissue remains, triggering the production of nacre. Keshi pearls are also encountered in mollusks that have successfully produced bead nucleated pearls. Experts theorize that in this latter case, cells displaced during the build-up of nacre on the nucleus initiate the growth of additional pearls. While first encountered in Akoyas, their South Sea and Tahitian counterparts became even more popular due their larger sizes, so much so that there was nothing “accidental” about South Sea production. Pearl farmers intentionally set conditions by using a small piece of mantle tissue to start their growth.

Multi colored gemstones, diamond, keshi pearls necklace by H. Stern. 
Courtesy of Heritage Auctions.

It seems that different authorities have different definitions of the term keshi and this creates confusion. The CIBJO Pearl Commission accepted the name “keshi” as a new name around 1998 but does not allow it to be classified as natural. The preferred term is “keshi cultured pearl” by their regulations. According to the CIBJO Pearl Book, keshi cultured pearl is a trade term that designates a non-beaded cultured pearl formed accidentally or intentionally by human intervention in marine pearl oysters such as the Akoya (Pinctada Fucata), Silver/Gold lipped (Pinctada Maxima) and Black lipped (Pinctada Margaritifera) oysters and is a byproduct of the culturing process.

There are two major differences between GIA educational material and CIBJO descriptions. First, one is about their formation. GIA strictly says that keshi is an accidental byproduct, whereas CIBJO adds the intentional production to its description. This simply justifies the production of South Sea keshi. The second discrepancy is in their origin. GIA accepts both marine and freshwater mollusks as the producer of keshi, but CIBJO only refers to marine species. GIA acceptance of freshwater origin stems from the keshi production of American freshwater pearl culturing. Technically, there is nothing to stop a freshwater mussel from producing keshi accidentally. The American Pearl Company has been selling keshi from their production and this particular product displays distinct features to separate it from the others.

Tahitian keshi pearl necklace. 
Courtesy of Bonhams.

As expected in today’s cultured pearl market, popularity and high price points of keshi resulted in a misleading product name “Cultured Freshwater Keshi.” China dominates the freshwater cultured pearl market of the world by mass production. Since the majority of freshwater cultured pearls are non-beaded, what is sold in the market as cultured freshwater keshi is not a true keshi by any description. This product is not accidental if GIA terminology is the criteria. Similarly, if CIBJO criteria is considered, then it is not from a marine species either.

Despite the discordance among authorities, most ethical dealers know and understand a true keshi by experience. Their acceptance changes depending on what regulations they prefer to follow. As a desirable product, keshi has established a niche in the market and will remain that way in the foreseeable future.

Photo in Header: 
Golden keshi pearls and diamond bracelet.
Courtesy of Sotheby’s.

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