In Go one of the players should play with black stones and the other player with white stones. But how to decide who plays with what colour of stones?
If you and your opponent have various levels and decide to play a handicap game, the problem is solved - the stronger player takes white stones and the weaker player puts the number of handicaps according to the difference in your Go ranks.
However, if you decide to play an even game, there should be made a lottery for the colour of stones.
For most of online Go matches - it’s quite simple, the computer makes the lottery.
For face-to-face tournament games - it depends on rules of each tournament, but usually the computer, while making the pairing, decides for the colours of players, too.
In other case - there is a traditional way of deciding the colours, it’s called “nigiri”.
Nigiri in Go - Traditional way of deciding the colours of the players
In both - Japanese and Chinese rules of Go - the older player takes a handful of white stones and puts the fist with grabbed stones on the board (in a way that nobody can see how many stones are inside).
The younger player chooses if the number of white stones in opponent’s hand is odd or even. To signalize odd number, the younger player puts one black stone on the board. To signalize even number, they put two black stones.
Then the older player opens their hand and counts the white stones.
At this point there is a slight difference whether the game is being played with Japanese or Chinese rules.
Nigiri in Go in Japanese rules:
If the younger player signalized the number correctly - they will play the game with the black stones.
If incorrectly - the older player will play with the black stones.
Nigiri in Go in Chinese rules:
If the younger player signalized the number correctly - they choose the colour of stones they want to play with.
If incorrectly - the older player chooses the colour of stones they want to play with.