Koshu crystal and precious stones carving

Koshu crystal and precious stones carving Koshu suisho kiseki zaiku

Mesmerizing delicate and richly expressive work
A brilliant encounter of natural gems and artisan passion


What is Koshu crystal and precious stones carving ?

Koshu Suisho Kiseki Zaiku are crystal and semi-precious gemstone carvings produced in Kofu City, Yamanashi Prefecture. Using traditional methods, natural gemstones are carefully cut, ground and polished to produce stunningly beautiful works of brilliant, colorful and transparent art. From olden times, Kofu had been known for its abundance of crystal, which gave rise to the production of crystal artifacts and works of art.
Koshu crystal carving is characterized by its extensive range of designs, including vibrantly alive animals, auspicious rising dragons, and charming modern characters much loved by children. Master artisans cut, carve and polish crystal; since the raw material is very hard, the grinding and cutting must be carried out very carefully as one slip and the work can shatter. A classic Koshu crystal carving technique is yukan meaning to carve crystal into chain-like shapes. To produce work of such delicacy and high quality requires craftsmen with a good eye for crystal and command of the highest traditional techniques.


The origins of the Koshu crystal carving date back to the Heian period (794-1192), when crystal gemstone was discovered in the Mitake Shosenkyo Gorge and Mt. Kinpu area in the north of Yamanashi Prefecture. The crystal was highly valued and often revered as a religious object in its own right. In the period from 1830 to 1844, artisans were invited from the Tamatsukuri area in Kyoto to teach the techniques for hand-polishing gems to local people. The Koshu polishing technique of spreading emery powder on an iron sheet, and smoothing gems by hand was established at this time, and ornamental items started to be made. In 1876, Shiro Fujimura, the governor of Yamanashi Prefecture, founded a municipal crystal processing department in Kofu, and encouraged training by sending artisans to study at technical courses in China. Unfortunately, by the end of the Meiji period the crystal had run out and the following Taisho period (1912-1926) saw Kofu capitalizing on its advanced polishing techniques to become a center processing imported crystal, agate, diamonds, and other precious stones. Once facilities were electrified, the area took up production of gemstone components for precision machinery.
After World War II, 80% of production was exported; however, following the 1971 dollar shock, the focus changed to making craft products for the domestic market and by making full use of traditional techniques and modern technology, their overall quality as art works was improved.

General Production Process

  1. 1. Selecting Gemstones The raw materials of Koshu crystal carving are usually crystal, agate, jade, or tiger’s-eye, and are mainly imported from overseas, although occasionally diamonds may be used. It takes considerable time to cut, grind, and carve such hard stones; they can be more than twice as hard as glass, which makes working the materials very difficult. The wide variety of Koshu crystal carvings are a testament to the skill, perseverance, and passion of the craftsmen.
    The first stage of production is the selection of the rough stone; dozens of stones may be rejected by the craftsman and it takes years of practice and a good feel for the piece to be made to choose the best quality. A skilled craftsman will have an almost magical ability to sense any hidden flaws and natural features, such as scratches or mistiness, and know how best to apply polishing techniques to bring out the secret beauty of the stone.
  2. 2. Line-Drawing and Cutting After selection, the stone is cut to shape and checked again for flaws and the like. It is important to clearly ascertain the section that is going to be removed from the rough stone and be used for the piece; once decided, guide lines are drawn and then cut with a powerful cutting machine.
  3. 3. Drawing the Design In this stage, the stone is assessed to ensure any natural features fit the overall design, and when the image is drawn onto the crystal, great attention is paid to its positioning. For example, in the case of a Buddha, it is important for the focal points such as the face to be positioned on an attractive part of the crystal; to ensure the appropriate proportions for the Buddha image, the entire balance of the figure must be taken into account, and the shoulders, hands and feet, and other detailed parts are also adjusted and drawn.
  4. 4. Kowari (Shaping) A high speed diamond drill is used to cut along the image lines and give a rough shape to the work piece; one slip and the work will be ruined, so this is quite a tense operation.
  5. 5. Rubbing After shaping, by using a variety of high-speed steel discs the work piece is roughly ground and polished closer to the final shape. The piece will be ground four times using ever-finer grades of emery powder, starting with coarse through to very fine.
  6. 6. Polishing The next stage is polishing rough surfaces using several different wooden discs; firstly a hard wood disc, followed by soft willow or paulownia wood, and then a final rubbing up with fine sand.
  7. 7. Finishing In the final stage, the rough gemstone from nature has all but disappeared only to be born again as a work of crystal art. The piece is put into a rotary barrel grinder along with round whetstone and chromic polishing powder and rotated until the required degree of shine is attained. Lastly, detailed parts are hand-finished by skilled craftsmen.

Where to Buy & More Information

Yamanashi Gem Museum

See other Semiprecious stone craftwork

See items made in Yamanashi