Gyokuseki ("Gyokusekikonko Puresu"; from Japanese, literally "gems and stones") is a logic puzzle created by Naoki Inaba (Japan). The aim is to fill a square grid with black circles ("gems") and white circles ("stones"). Every row and every column contains one black circle and random quantity of white circles. A number at the edge of the puzzle indicates how many circles can be seen in the corresponding row or column up to and including the black circle. brain games for adults - brain teasers riddles - mind puzzle games - mind puzzles for adults - puzzle games for adults - brain busters - math brain teasers - brain teasers and answers - riddles and brain teasers - brain twister - mind teaser puzzles - mind games for adults - funny puzzles - mental puzzles