Grand Tour Circular two toned onix with a Classical “Greek key” pattern set in gold and diamonds. England ca 1820.
Measurements : 30 mm in diameter
Various claims have been made for what a Greek key means. There may be a connection with the labyrinth where Theseus fought the Minotaur. A Greek bowl in the British museum shows Theseus dragging the Minotaur from the labyrinth, which is indicated by a Greek key frieze. You can make a Cretan or classical maze using a Greek key, and many mazes have Greek keys embedded in a design, especially Roman mazes.
Other suggested meanings are stylised waves, snakes, symbolizing the bonds of love, friendship and devotion, eternal life, the four cardinal points, the meander of life, creative energy, the four seasons, etc. Take your pick! I prefer the waves. There are curved forms of Greek keys which look very like seawaves. This pattern Curved Greek key is on the shield of Philip, father of Alexander the Great. The shield also has a more conventional Greek key pattern. This website only describes the square forms.