Clam-Shell Go Stone Grades (Yuki, Tsuki, Hana): Differences and How to Choose

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The short answer: grade is set by the striations of the white clam-shell stone

The grade of clam-shell (hamaguri) go stones is set by the fineness and evenness of the shell’s growth lines (shimame), and is usually given in three tiers, top to bottom: Yuki (snow), Tsuki (moon), Hana (flower). Grade is a measure of beauty and rarity, not necessarily of how the stone plays. Understand grade, thickness (go), and origin as three separate axes and you can choose a satisfying set for your budget.

What sets the grade

Clam-shell stones are cut and polished from clam shell; the growth striations on the surface set the grade — the finer, straighter, and more even they are, the higher the grade. Grade is decided by the white stone; the black Nachiguro also varies in quality, but it’s the white stone’s grade and thickness that drive a set’s price. Being natural, each stone differs slightly even within a grade — part of the appeal.

Yuki, Tsuki, Hana

• Yuki (snow): the top grade — very fine, straight, even striations; notably white and refined; rare and priced highest.
• Tsuki (moon): next tier — slightly broader striations but well ordered; an excellent balance of beauty and price.
• Hana (flower): broader or more varied striations; an approachable tier that still gives the full feel of natural clam shell.

Grade names and tiers vary a little by shop, so confirm the actual striations in person at a trusted specialist.

Grade vs. thickness (go)

Grade (striations = beauty/rarity) and thickness (go = weight of play, presence, price) are separate axes. A larger go is thicker, with a weightier sound and feel. “Yuki in a thick go” is the top; “Hana in a thin go” is the most approachable. To decide a budget: raise the grade for refinement and pride of ownership, raise the go for a weighty sound and board presence.

Grade and origin

Hyuga (Miyazaki) clam is the domestic peak — thick, beautifully striated, scarce, and priced accordingly. Mexican clam supplies most of the market across a wide range of grades and thicknesses, easy to choose for a budget. Grade is set by striations, but at the same grade, origin still shifts rarity and price.

Choosing by budget

• Special or gift set: Hyuga Yuki, thick — rarity and prestige first.
• Quality and budget: Tsuki at a medium-to-thick go — the satisfying mainstream.
• Practical and value: Hana at a medium go — natural clam shell enjoyed easily.

FAQ

Is the grade set by the black stone too?

No. Grade is set by the white clam-shell stone’s striations. The black Nachiguro varies in quality, but the white stone drives a set’s grade and price.