Keshi Pearls History + Characteristics

Assorted Keshi Pearls. Photo license: Creative Commons.   Keshi pearls owe their name to the poppy seed. These small, oddly-shaped pearls actually represent the byproduct of the cultured pearl industry. Their unique characteristics, of course, make them a favorite among collectors.  

Characteristics of Keshi Pearls

First of all, keshi pearls are non-nucleated. While non-nucleated pearls sometimes form naturally as a result of intrusion, primarily they form only when intentional nucleation fails. To create a cultured pearl, a technician carefully implants a small piece of mantle, sometimes called a button, into a mollusk. Sometimes, early in the process, pieces of this inserted mantle tissue fracture, causing the formation of separate pearl sacs without solid nuclei. This results in the formation of a small, flat, oddly-shaped pearl. Without a nucleus, these pearls are comprised completely of nacre. As such, they form in a variety of colors and radiate with intense luster. These happy accidents used to happen en masse, particularly in the early days of Japan's Akoya pearl production.  

Japanese Keshi Pearls

In the 1920s, the Japanese began culturing Akoya pearls. After the first harvest, they discovered numerous tiny pearls they called keshi, a Japanese term that means "poppy." Though they hesitated to discard these highly lustrous nacre treasures, they also desired to spare themselves the tedium of sorting, stringing, and marketing these seed pearls. Fortunately, Indian tradesmen swiftly bought out the Japanese supplies of keshi pearls, knowing full well their Arab customers would believe they grew naturally. Not surprisingly, their story sold, as did the pearls. In truth, these small pearlescent wonders are not considered natural pearls, as they are an unintended consequence of pearl cultivation.  

What's In A Name?

Cross-cultural controversy continues in the labeling of keshi pearls. The official use of the term keshi, sanctioned by the gem trade industry, refers only to those non-nucleated nacre formations which arise from the culturing of saltwater pearls. However, some use the term to describe freshwater non-nucleated pearls, as well. While this label may technically fit, industry leaders prefer the use of other terms for freshwater occurrences. The Chinese adopted the most recent use of the term in their freshwater practices. Chinese freshwater pearl culturing includes a practice called second (or subsequent) harvest. Once a mollusk produces its first cultured pearl, technicians typically implant a second nucleus. This time around, the mollusk produces nacre at a much slower rate. This slower rate of production often results in somewhat flattened baroque shapes. The Chinese adopted the term keshi to describe these second harvest pearls. Today, true keshi pearls occur far more rarely. Current practice includes the use of x-rays, which allow technicians to observe the rejection of a nucleus early enough to intervene. Re-nucleation usually prevents the growth of a keshi pearl. Of course, their rarity now renders them a collector's dream.