**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.

**Cross+A** can solve puzzles from **4 x 4** to **9 x 9**.