JA
PROJECT
Jewelry Brand “KOHKOH” Illuminating Social Issues
CASTEM has launched KOHKOH, a future-oriented jewelry brand that utilizes its patented pearl cultivation technology, and has opened an online store.
Online store: https://store.kohkoh-jewelry.com/
KOHKOH places strong emphasis on environmentally friendly and sustainable jewelry manufacturing.
As global awareness of “ethical” practices and the SDGs continues to grow, the brand transforms large quantities of discarded mother-of-pearl oysters generated during the pearl cultivation process into new jewelry pieces.
Furthermore, by leveraging CASTEM’s advanced 3D modeling technology, the brand has succeeded in cultivating freely shaped pearls that challenge the conventional notion that pearls must be round. This technology was patented in Japan in 2022. KOHKOH continues to release new works that combine pearl cultivation with metal processing expertise to create innovative art jewelry.
In 2024, at New Jewelry TOKYO 2024, Japan’s largest designer jewelry event held in Aoyama, Tokyo, the brand achieved the remarkable distinction of winning both the Best Jewelry Award and the Audience Award. In the following year, it also received the Audience Award at New Jewelry TOKYO 2025.
The brand is produced under the advisory direction of internationally active jewelry artist Takashi Kojima. We interviewed him about the brand’s philosophy and future outlook.
In 2024, at New Jewelry TOKYO 2024, Japan’s largest designer jewelry event held in Aoyama, Tokyo, the brand achieved the remarkable distinction of winning both the Best Jewelry Award and the Audience Award. In the following year, it also received the Audience Award at New Jewelry TOKYO 2025.
The brand is produced under the advisory direction of internationally active jewelry artist Takashi Kojima. We interviewed him about the brand’s philosophy and future outlook.
Philosophy Behind “KOHKOH”
The brand name “KOHKOH” is inspired by the luster of pearls.
It also embodies the idea of “thinking about the light,” reflecting our commitment to illuminating social issues while exploring solutions through new technologies and materials.
It also embodies the idea of “thinking about the light,” reflecting our commitment to illuminating social issues while exploring solutions through new technologies and materials.
Recycling mother-of-pearl oysters that would otherwise be discarded represents one step toward addressing these issues. While beginning his own pearl cultivation in 2018, Kojima observed the significant volume of shells and pearls discarded during the cultivation process, including many failed pearls.
In recent years, while the use of fur and leather has increasingly become taboo in the apparel industry, he questioned why the sacrifice of living pearl oysters has received relatively little attention. Through KOHKOH jewelry, the brand aims to raise awareness of this issue.
In recent years, while the use of fur and leather has increasingly become taboo in the apparel industry, he questioned why the sacrifice of living pearl oysters has received relatively little attention. Through KOHKOH jewelry, the brand aims to raise awareness of this issue.
Patented Technology for Forming Nacre Layers on 3D-Printed Cores
KOHKOH spent more than two years developing its pearl cultivation technology and successfully achieved freely shaped pearl formation.
Using high-precision 3D printers, cores in various shapes—such as letters and figures—are produced. These cores are implanted into pearl oysters and returned to the sea, where nacre layers form over approximately six months.
Using high-precision 3D printers, cores in various shapes—such as letters and figures—are produced. These cores are implanted into pearl oysters and returned to the sea, where nacre layers form over approximately six months.
The brand’s signature “Light” series uses CT scanning of individual gemstones to create cores that precisely match the stones’ dimensions. Nacre layers are then formed over these cores, producing pieces in which pearls and gemstones integrate seamlessly. The visually striking designs have been highly praised by customers worldwide.
The new 2025 “Cover” series features pearls engineered to perfectly envelop gemstones, enabling the pearl to be appreciated from above while revealing both pearl and gemstone from the side—an entirely new jewelry concept.
KOHKOH also produces pearls in diverse shapes, including initials, cameos, and half-moon forms. Because cultivation requires approximately six months, early inquiries are recommended.
KOHKOH also produces pearls in diverse shapes, including initials, cameos, and half-moon forms. Because cultivation requires approximately six months, early inquiries are recommended.
A New Era of Cameo Realized Through Precision Machining
KOHKOH manufactures jewelry using advanced machining technology.
While the jewelry industry typically relies on specialized polishers and gem cutters, KOHKOH performs stone cutting, shell cutting, and blasting in-house. Cameos—relief carvings traditionally made on shells or semi-precious stones—are also produced using precision cutting machines.
This enables extremely fine expression in 0.001 mm increments that cannot be achieved by hand. The consistent cutting force also reduces the risk of cracking due to excessive pressure.
While the jewelry industry typically relies on specialized polishers and gem cutters, KOHKOH performs stone cutting, shell cutting, and blasting in-house. Cameos—relief carvings traditionally made on shells or semi-precious stones—are also produced using precision cutting machines.
This enables extremely fine expression in 0.001 mm increments that cannot be achieved by hand. The consistent cutting force also reduces the risk of cracking due to excessive pressure.
Based on jewelry designs, 3D CAD data is generated and machining is performed accordingly. Because mother-of-pearl is a natural material, each piece has unique geometry. Processing positions are adjusted to the 0.1 mm level for each individual piece.
Intricately carved cameos utilizing nacre layers as thin as 0.12 mm have proven especially popular.
While incorporating classical motifs such as faces, figures, and animals, KOHKOH creates modern cameos that combine precision and delicacy.
Diverse Jewelry Leveraging CASTEM Technologies
Jewelry that integrates industrial technology offers a fresh and distinctive appeal. This represents a unique strength derived from CASTEM’s proprietary technological resources.
In addition to cameos, the brand develops a wide range of jewelry using mother-of-pearl and other advanced materials.
For example, the “Stone Frame” series uses gemstones themselves—rather than metal—for settings and frames. Quartz is precisely cut to match the shape of the main blue topaz stone using proprietary techniques.
Because quartz-based materials are extremely hard, slight increases in machining conditions can cause edge chipping, making processing highly challenging. In some cases, machining a single piece can require up to 20 hours.
In addition to cameos, the brand develops a wide range of jewelry using mother-of-pearl and other advanced materials.
For example, the “Stone Frame” series uses gemstones themselves—rather than metal—for settings and frames. Quartz is precisely cut to match the shape of the main blue topaz stone using proprietary techniques.
Because quartz-based materials are extremely hard, slight increases in machining conditions can cause edge chipping, making processing highly challenging. In some cases, machining a single piece can require up to 20 hours.
The “Imitation” series features pendants with a single silver sphere placed on mother-of-pearl. Depending on the viewing angle, reflected light creates the visual illusion of a floating pearl.
Another cameo series intentionally preserves the outer rim—an uncommon approach inspired by a CASTEM employee who is also a watchmaker. These works preserve the natural form of the mother-of-pearl while creating jewelry designs never seen before.
Future Vision — Jewelry to Be Cherished for the Next 100 Years
Since launching the brand in 2023, KOHKOH has continuously pursued the creation of “unprecedented jewelry” that sheds light on social issues.
At New Jewelry TOKYO 2024, the brand received both the Best Jewelry Award and the Audience Award, demonstrating growing recognition of its SDGs-conscious approach.
Looking ahead, we plan to collaborate with art galleries and challenge ourselves to create art pieces that utilize nacre layers. We also aim to develop new products using powders made from discarded pearls and leftover mother-of-pearl materials. Through jewelry creation and manufacturing, we hope to contribute to solving social issues.
KOHKOH values jewelry that can only be created in the present era—pieces born from today’s 3D technologies and advanced processing, yet timeless enough to be cherished 100 years into the future. With global expansion in mind, the brand will continue to embody this vision.
At New Jewelry TOKYO 2024, the brand received both the Best Jewelry Award and the Audience Award, demonstrating growing recognition of its SDGs-conscious approach.
Looking ahead, we plan to collaborate with art galleries and challenge ourselves to create art pieces that utilize nacre layers. We also aim to develop new products using powders made from discarded pearls and leftover mother-of-pearl materials. Through jewelry creation and manufacturing, we hope to contribute to solving social issues.
KOHKOH values jewelry that can only be created in the present era—pieces born from today’s 3D technologies and advanced processing, yet timeless enough to be cherished 100 years into the future. With global expansion in mind, the brand will continue to embody this vision.
Profile of Takashi Kojima
-Founder of FACILE jewelry
-Part-time Lecturer at Kobe Design University
-Director of the Japan Jewelry Designers Association
-Representative of Contemporary Jewellery Symposium Tokyo
Born into an artistic family—with a Japanese-style painter father and a craft artist mother—Kojima studied architecture at university while simultaneously learning metalworking techniques in evening classes.
He began his career as a jewelry artist in 2005 and opened an atelier shop in Kyoto in 2010. Around 2011, he expanded his activities overseas, and today most of his exhibitions are held internationally.
In recent years, he has focused on activities that transcend traditional jewelry, including contemporary art gallery exhibitions and collaborations with contemporary artists. His works are now part of permanent museum collections in the Netherlands, France, and Switzerland.
-Part-time Lecturer at Kobe Design University
-Director of the Japan Jewelry Designers Association
-Representative of Contemporary Jewellery Symposium Tokyo
Born into an artistic family—with a Japanese-style painter father and a craft artist mother—Kojima studied architecture at university while simultaneously learning metalworking techniques in evening classes.
He began his career as a jewelry artist in 2005 and opened an atelier shop in Kyoto in 2010. Around 2011, he expanded his activities overseas, and today most of his exhibitions are held internationally.
In recent years, he has focused on activities that transcend traditional jewelry, including contemporary art gallery exhibitions and collaborations with contemporary artists. His works are now part of permanent museum collections in the Netherlands, France, and Switzerland.
Please stay tuned for our upcoming new pieces and activities.
《Online Shop》 https://store.kohkoh-jewelry.com/
《Instagram》 https://www.instagram.com/kohkoh_jewelry/?hl=ja
《 JEWELRY JOURNAL Interview with Takashi Kojima》
Part 1:https://www.jewelryjournal.jp/interview/41835/
Part 2: https://www.jewelryjournal.jp/whatsnew/41871/