A simple flat disk is the setting for this tiny triple moon symbol. The symbol really stands out against its setting not only because it's raised above the surface of the disk, but also because there's a dark nebulous band of heavy oxidation running across the disk behind it that makes the plain polished forms of the crescent and full moons pop out in contrast.
The ancient Triple Moon symbol stands for the three traditional phases of a woman's life: the Maiden as represented by the waxing crescent moon, the Mother in the form of the full moon, and the Crone symbolized by the waning crescent moon.