囲碁将棋盤榧寿堂／ Caring for Go Stones: Clamshell Yellowing, Nachiguro Black, and Why You Should Not Bleach Them

Caring for Go Stones: Clamshell Yellowing, Nachiguro Black, and Why You Should Not Bleach Them

Go stones look indestructible, which is exactly why they get mistreated. The white stones in a good set are cut from clamshell (hamaguri, 蛤), a natural shell. The black stones are often nachiguro (那智黒), a natural black stone. Both are spoiled by the cleaning methods people reach for first: bleach, detergent, scouring.

The right approach to go stone care is less about removing yellowing and dirt than about not letting it progress: wipe off hand oil regularly, and store the stones properly.

The short version

Daily care is a dry wipe with a soft cloth.
No detergent, bleach, abrasives or melamine sponges on clamshell or nachiguro stones.
Yellowing of clamshell stones is a natural ageing process, and fully reversing it is often not possible.
Store stones in their bowls (goke), away from humidity and direct sun.
When chipped stones accumulate, replace them rather than playing on.

The basic routine

Like the board, go stones are cared for mainly by dry wiping. A quick wipe with a soft cloth after a game greatly reduces the build-up of skin oil, sweat and dust. In summer, when hands are oilier, wipe more often: it slows yellowing and dulling.

Wiping 180 white and 181 black stones one by one is tedious, so many players do it in batches: a handful at a time as they put them away. Wiping before the stones go back into the bowls keeps the whole set evenly conditioned. Doing it together with the board’s dry wipe is efficient; the board itself is cared for on the same principle: dry, gentle, and away from water.

Glass and resin stones are far less delicate, but the same habit keeps them looking clean.

Clamshell (white stones)

Most traditional white stones are cut from clamshell. Each stone shows its own pattern of fine stripes (shime, 縞目), which is part of the appeal. Being natural shell, clamshell is weak against strong chemicals and friction. Damage the surface and the texture is lost for good. Gentle handling is the whole principle.

If you are buying, the grades and origins are covered in Clam-Shell Go Stone Grades and Suwabute or Mexican?

Nachiguro (black stones)

Natural black stones such as nachiguro are hard, but rubbing with abrasives can leave uneven patches of sheen. Dry wiping is the rule here too; avoid hard rubbing.

Yellowing and dirt: what is realistic

Yellowing of clamshell stones is the thing owners worry about most. Know this first: much yellowing is natural ageing of the shell, together with hand oil accumulated over years, and returning the stones to their original white is usually not possible. “Stop it getting worse” and “make it less noticeable” are realistic goals; “brand new” is not.

What you can try

Dry-wipe to remove surface oil and dust. This alone can lift some dullness.
If that is not enough, wipe lightly with a cloth wrung out until almost dry, then dry the stone immediately with a dry cloth. Clamshell left wet can stain, so never leave stones damp and never soak them.
Stop there. Do not use detergent, bleach, vinegar, toothpaste or abrasives, even on heavy dirt. A stone may look whiter for a while, but its surface has been eaten away, the texture is gone, and the roughened surface picks up dirt faster.

What not to do

Soaking stones in bleach or dish detergent.
Rubbing with melamine sponges, sandpaper or abrasives.
Putting stones in a dishwasher, or washing them under water for long.
Drying stones in direct sunlight (discolouration, drying out).

A set of clamshell stones that has yellowed evenly over a lifetime of play can simply be accepted as character. If you really want a fresh look, or many stones are chipped, think about replacement instead.

Storage

Go stones are stored in their bowls (goke, 碁笥). The points overlap with board care:

Keep them somewhere dry. Putting stones away in a damp bowl invites mould and discolouration.
Keep them out of direct sunlight.
Do not handle them with wet hands, and wipe them before putting them away.
Wooden bowls need dry care too. Many goke are wood; do not wipe them with water.

In humid climates, do not store the bowls right beside a dehumidifier or an air-conditioning outlet; the swing between damp and dry is harder on natural materials than steady conditions. Bowls themselves are covered in How to Choose Go Bowls and Go Bowl Woods and What the Price Ladder Actually Buys.

Replacing chipped stones

Over years of play, some stones chip or crack. A few are not a problem, but once chips multiply they distract during games and spoil the look of the board.

Top-ups are often possible if you match the type and the size number (gō, 号, which indicates thickness). In Japan, single clamshell stones are sold individually; one Japanese go shop’s official online store lists them at 231 yen each for size 28 and 187 yen each for size 25 (including tax, checked 2026-10-06 at Syogoya, an Osaka go and shogi shop: https://www.syogoya.co.jp/shopbrand/goisi-hamaguri/ ). Size numbers are explained in Go Stone Sizes Explained.
New shell will not match old shell exactly. Clamshell is natural, so colour and stripes of new stones may differ from your yellowed set.
If the whole set has yellowed and many stones are chipped, buying a new set may be more satisfying in looks and feel than patching.

Before deciding, note the type, size number and condition of your stones and ask a go equipment specialist. Whether top-ups are available varies by shop and by stone type, so ask before ordering.

FAQ

Can yellowed clamshell stones be made white again? Usually not completely; the main cause is natural ageing of the shell. Dry wiping can reduce dullness, but bleaching or polishing ruins the texture. Aim to stop it progressing.

Can I wash go stones in water? Not recommended. Clamshell can stain if moisture remains. If you must remove dirt, wipe lightly with a cloth wrung almost dry, dry immediately, and never soak them.

Is the care different for black and white stones? The basic dry wipe is the same, and both should be kept away from abrasives and hard rubbing. Nachiguro in particular can show uneven sheen if rubbed hard.

Can I buy replacements for just the chipped stones? Often, if the same type and size number are available. Colour and stripes may not match exactly, as clamshell is natural. Ask a specialist with your stones’ details.

This page summarises general care for go stones (checked October 2026). Advice can differ by material and maker; confirm with a specialist for a particular set. We are an independent guide. We do not stock stones, but we can order them from makers and shops in Japan for you — see Ordering from overseas.