Editing Go (game) (section)

==== Stones ====
A full set of Go stones (''goishi'') usually contains 181 black stones and 180 white ones; a 19×19 grid has 361 points, so there are enough stones to cover the board, and Black gets the extra odd stone because that player goes first. However it may happen, especially in beginners' games, that many back-and-forth captures empty the bowls before the end of the game: in that case an exchange of prisoners allows the game to continue.

Traditional Japanese stones are double-convex, and made of [[clam]]shell (white) and [[slate]] (black).{{sfn|Fairbairn|1992|pp=150–153}} The classic slate is nachiguro stone mined in [[Wakayama Prefecture]] and the clamshell from the Hamaguri clam (''[[Meretrix lusoria]]'') or the [[Korean hard clam]]; however, due to a scarcity in the Japanese supply of these clams, the stones are most often made of shells harvested from [[Mexico]].{{sfn|Fairbairn|1992|pp=150–153}} Historically, the most prized stones were made of [[jade]], often given to the reigning emperor as a gift.{{sfn|Fairbairn|1992|pp=150–153}}

In China, the game is traditionally played with single-convex stones{{sfn|Fairbairn|1992|pp=150–153}} made of a composite called [[Yunzi]]. The material comes from Yunnan Province and is made by [[sintering]] a proprietary and trade-secret mixture of mineral compounds derived from the local stone. This process dates to the Tang dynasty and, after the knowledge was lost in the 1920s during the [[Chinese Civil War]], was rediscovered in the 1960s by the now state-run Yunzi company. The material is praised for its colors, its pleasing sound as compared to glass or to synthetics such as [[melamine]], and its lower cost as opposed to other materials such as slate/shell. The term ''yunzi'' can also refer to a single-convex stone made of any material; however, most English-language Go suppliers specify Yunzi as a material and single-convex as a shape to avoid confusion, as stones made of Yunzi are also available in double-convex while synthetic stones can be either shape.

Traditional stones are made so that black stones are slightly larger in diameter than white; this is to compensate for the optical illusion created by contrasting colors that would make equal-sized white stones appear larger on the board than black stones.{{sfn|Fairbairn|1992|pp=150–153}}{{efn|1=See [[Overshoot (typography)|Overshoot]] in Western typography for similar subtle adjustment to create a uniform appearance.}}

[[File:Bowls dwindsor.jpg|thumb|left|An example of single-convex stones and ''Go Seigen'' bowls. These particular stones are made of [[Yunzi]] material, and the bowls of jujube wood.]]