囲碁将棋盤 榧寿堂 ／ Suwabute or Mexican? What “Clamshell” and “Hon-Kaya” Actually Mean When You Buy
Suwabute or Mexican? What “Clamshell” and “Hon-Kaya” Actually Mean When You Buy
If you are looking at a listing that says “clamshell go stones”, the word alone tells you very little. Clamshell stones are made from at least two completely different shells, from opposite sides of the world, and the price gap between them is enormous. This page explains what separates them, and what “hon-kaya” means when you see it on a board.
Not all clamshell is the same shell
Two sources dominate the market:
| Hyuga Suwabute (日向スワブテ) | Mexican clamshell | |
|---|---|---|
| Origin | Okuragahama beach, Hyuga City, Miyazaki, Japan | Mexico |
| Availability | Depleted since around 1990; increasingly scarce | The normal commercial source today |
| Reputation | Called “the legendary go stones” | Standard for good-quality stones |
The Suwabute shell grew thick because it had to: it developed in rough surf, and thickened to survive the impact. That thickness is exactly what a stone-maker needs, and it is why the supply cannot simply be replaced from elsewhere.
Practical consequence for a buyer: almost every “clamshell” stone sold new today is Mexican shell. That is not a defect — it is the good, normal product. But if a seller implies Japanese shell without saying so, the burden of proof is on them.
Why the craft limits supply as much as the shell does
Shell is only half of it. A craftsman needs roughly 15 years to master the work, and can finish only about 100 stones a day. A full set is 361 stones. The arithmetic explains the price of top stones better than any marketing copy does.
Hand-polishing (tezuri) is what produces the particular roundness that players describe as the difference in feel. It is not a surface finish applied at the end; it is the shaping itself.
“Hon-kaya” is a species, not a grade
The same confusion happens on the board side. Hon-kaya is Japanese Torreya (Torreya nucifera). Shin-kaya is not young or lesser kaya — it is a different tree entirely, usually spruce. They are not two grades of one material.
Hyuga kaya, the most prized source, is barely produced as new stock: cutting in the national forest largely ended, so what circulates is old stock and antiques. This is why so many “hon-kaya” boards you find abroad are vintage listings rather than new products.
See Honkaya vs Shinkaya for the full comparison.
What to actually ask a seller
- For stones: which shell, and what size number? Size is thickness — see Go Stone Sizes Explained. Ask for grade separately; grade and thickness are independent.
- For a board: is it kaya (Torreya) or shin-kaya (spruce)? Straight grain (masame) or flat grain (itame)? New or vintage?
- For anything vintage: ask about cracks and warping before condition photos are cropped. Thickness resists warping — see board thickness.
None of these questions require expertise to ask. They only require knowing that the categories exist.
Sources. Suwabute origin, the post-1990 depletion, the “legendary go stones” description, the 15-year training and ~100 stones per day: Hyuga Goboard & Stone (en.goboard-stone.co.jp). Hyuga kaya and the end of national-forest cutting: the same maker. Checked 2026-08-18. We do not stock equipment, but we can order it from Japan for you (see Ordering from overseas); confirm any specific item with the seller.