Well we know that members of akatuski wear rings and they have them in different fingers...
It determines their position in the pair of hands they stand on when they extract a tailed beast , it has some special meanings and it also symbolises that they are part of akatsuki
Right thumb: 零 (rei, "zero"); worn by Pain,
Right index finger: 青 (sei, shō, "blue," "green"); worn by Deidara.
Right middle finger: 白 (bya, "white"); worn by Konan.
Right ring finger: 朱 (shu, "vermilion," "scarlet"); worn by Itachi Uchiha.
Right little finger: 亥 (gai, "sign of the boar"); worn by Zetsu,
Left little finger: 空 (kū, "sky," "void"); worn by Orochimaru.
Left ring finger: 南 (nan, "south"); worn by Kisame Hoshigaki.
Left middle finger: 北 (hoku, "north"); worn by Kakuzu.
Left index finger: 三 (san, "three"); worn by Hidan.
Left thumb: 玉 (gyoku, "jewel," "ball," also the black king in shogi); worn by Sasori and later by Tobi.
It determines their position in the pair of hands they stand on when they extract a tailed beast , it has some special meanings and it also symbolises that they are part of akatsuki
Right thumb: 零 (rei, "zero"); worn by Pain,
Right index finger: 青 (sei, shō, "blue," "green"); worn by Deidara.
Right middle finger: 白 (bya, "white"); worn by Konan.
Right ring finger: 朱 (shu, "vermilion," "scarlet"); worn by Itachi Uchiha.
Right little finger: 亥 (gai, "sign of the boar"); worn by Zetsu,
Left little finger: 空 (kū, "sky," "void"); worn by Orochimaru.
Left ring finger: 南 (nan, "south"); worn by Kisame Hoshigaki.
Left middle finger: 北 (hoku, "north"); worn by Kakuzu.
Left index finger: 三 (san, "three"); worn by Hidan.
Left thumb: 玉 (gyoku, "jewel," "ball," also the black king in shogi); worn by Sasori and later by Tobi.