Koshu Crystal Gemstone is The Outstanding Art of Japanese Craftmanship


What is Koshu Crystal Gemstone Work?

Koshu Crystal gemstone work is a Japanese traditional craft using natural gemstones produced in Fuefuki-shi, Yamanashi Prefecture, which is blessed with rich forests and water resources. Precious stones such as quartz, jade, jasper, obsidian, and agate are mainly used. The products range from indoor figurines in the shape of Buddhist statues, animals, and birds to ornaments such as necklaces, rings, and brooches. Quartz crystal, which is more than twice as hard as glass, is processed slowly and over time.

The transparent color and brilliance of natural precious stones produced by nature. Koshu Crystal Gemstone crafting is characterized by the use of the most sophisticated carving and careful polishing techniques, which add beauty through life’s sensitivities to the superior taste of natural gemstones.

Koshu crystal gemstone work
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Main Characteristics

Because the material is natural stone, the size and shape are limited. Plus, as it is more than twice as hard as glass, it is very difficult to process and takes a great deal of time to shape. The composition of each type of stone differs, so some are more tenacious than others and some are more fragile than others.

It is such a popular craft that some products are exported not only within Japan but also to other countries. Furthermore, it is used in a variety of settings, such as in the dedication of works to the imperial family in the shape of the animals of the Chinese zodiac. Or, we often see dragons

Historical Background of Koshu Crystal Gemstone

1. Koshu Kiseki-zaiku originated about 1,000 years ago

Koshu Kiseki-zaiku began to be produced in Yamanashi Prefecture about 1,000 years ago. It is said that the origin of Koshu kiseki-zaiku dates back to the discovery of rough crystal stones deep in the Mitake-Syosenkyo Gorge, and the craftsmen began to make products using these stones.

At the time the rough stones were discovered, there was no technology for processing them, and they were displayed in their original state. As time progressed into the Edo period (1603-1867), craftsmen were invited from Kyoto, and the technique developed. The craftsmen developed a method of processing quartz by sprinkling Kongo sand on an iron plate and polishing the quartz.

2. Significant development from the Meiji to Taisho periods

Once quartz crystals were processed in the Edo period, the technology gradually developed from there. In the Meiji Era (1868-1912), the foot-operated rotary crystal processing technique was invented, and speedy and careful processing began to be applied to quartz crystals. As time progressed further into the Taisho era (1912-1926), the technology evolved from manual processing to electric power processing, which allowed for more efficient operations. In the Taisho era (1912-1926), manual processing evolved into electric power processing, which made it possible to work more efficiently.

3. Exhibited at the Paris Expo

Koshu quartz crystal work was exhibited at the first Paris Expo, attracting attention not only in Japan but also around the world. The technique of engraving quartz crystals was rare, and it is said to have been very well received overseas.

4. Designated as a traditional craft on June 2, 1976

In 1976, it was designated as a traditional craft by the Ministry of Economy, Trade and Industry. These highly artistic works are still attracting attention from all over the world.

Koshu Crystal gemstone work in Japan
Source: Craftsman’s Style (Yamanashi prefecture)

Manufacturing Process

1. Sorting of gemstones

The raw materials used for Koshu quartz crystal work include quartz, agate, jade, and torameshi (tiger’s-eye stone). Cutting and carving hard stones is an extremely time-consuming process. Quartz, in particular, is more than twice as hard as glass, making it very difficult to process. The craftsmen’s skill, perseverance, and passion for their work produce many splendid Koshu Crystal Gemstone works.

The first step in the Koshu Crystal Gemstone work process is the sorting of the gemstones. The craftsman’s many years of experience and intuition allow him to select from dozens of rough gemstones the ones that best suit the piece. The gemstones are mainly imported from overseas, and include quartz, diamonds, and a wide variety of other gemstones, so it is necessary to select gemstones while considering the characteristics of the gemstones and the appropriate polishing techniques. The craftsman’s discernment is required to determine if there are any blemishes or blemishes within the stone that do not show on the surface.

2. Drawing and cutting

Once the gemstones have been sorted, they are cut to the appropriate size so that they can be used to create the finished workpiece. It is important to determine the portion of the gemstone that can be used in the creation of a piece of precious stone work. Once the area to be used is determined, a line is drawn as a guide, and the hard stone is cut along the line using a large machine for cutting the rough stone.

3. Painting

Paintings are made on the cut stone, considering how the stone will be used to give shape to the design you want to create. For example, in the case of a Buddha statue, it is important to design the face and other focal points of the statue so that the best features of the stone can be seen. In addition, we draw detailed parts such as shoulders, arms and legs to create the image of the Buddha statue, while maintaining the overall balance of the statue so that it will be six heads tall.

4. Kowari

In accordance with the drawing made in the painting process, excess stones are carefully removed from the larger stones to bring them closer to the shape of the finished product. This is a nerve-wracking process in which incisions are made using diamonds spinning at high speed.

5. Rough grinding

After the process of small division is completed, it is time for the rough grinding process. Turning a circular iron sesame at high speed while changing to various types of frames, the stones are placed against them and shaved into precise shapes. The abrasive used to grind the stone is called Kongo sand. At first, coarse grains are used, then gradually changed to finer grains, and the stone is ground four times.

6. Polishing

Once the coarse grains have been ground, the stone is moved on to the polishing process. This is the process of rubbing and polishing the rough areas that have been scraped off with iron using a wooden frame. First, hard wood is used for polishing, then soft willow and paulownia wood, and then fine sand (alexan) is used to polish the stone.

7. Finishing

The final step is the process of transforming the precious stones mined from nature into works of art. A rotary polisher (parallel) is filled with a rounded grinding stone (Tipton) and a polishing powder called chromium oxide (blue-green algae). The stone work is placed in the parellel, and the container itself is rotated to produce a gloss that matches the work. Finally, the fine details are finished by hand by a skilled craftsman.

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