Mention is made in a late Edo period (1600-1868) ""shopping guide"" for Kofu, the capital of Yamanashi prefecture, that seals were being sold and skilled craftsmen were making blocks and seals in wood.
In another document dating from the same period, there is an order for a rather rare kind of quartz containing grass and for water buffalo horn from which to make seals. This would seem to prove that already during the second half of the 19th century, all manner of seals were being produced in Kofu.
The shear degree of development of the carving skills, the preparation of materials for making seals including the polishing of quartz as well as the use of boxwood and horn, has reached a level of organization that can not be found in any other prefecture in Japan. All the specialists including the carvers and seal marketing specialists can be found at work in Yamanashi prefecture and the situation is the same today as it has always been.
Beginning with the long developed techniques to carve seals from crystal and then etch their intricate characters, the craftsmen of Yamanashi prefecture expanded their craft to carve name seals from Japanese boxwood and water buffalo horn, to create an expansive seal carving craft that can only be found in Yamanashi. The craftsmen who carve the seal bases, etch the characters and sell the finished name seals are all gathered in Yamanashi prefecture, and even today all aspects of the craft continue thrive in the prefecture.
How to make
While the steps vary slightly depending on whether the seal is made of boxwood, water buffalo horn or crystal, the primary steps of creating a seal are: smoothing the seal surface, deciding the lettering style, drawing the letter template on Japanese washi paper, drawing the lettering template onto the seal, carving the letters into the seal, smoothing the carved surface, adjusting the carved letters after checking them with charcoal ink, and finally polishing the seal to complete the product. A variety of traditional hand tools are used in the process of producing the seal including: carving knives, seal engraving knives, round knives, flat knives, hand chisels, a tapping mallet, carving stand, and seal clamp - every step of producing of the seal is completed by hand. In particular, the delicate and arduous handwork of carving the letters into the seal and then adjusting them until they are perfect produces a unique seal that is truly one of a kind in the world.