The Mexican Bola ball, also known as a Harmony necklace, is a musical chime necklace first worn by pregnant women in Mexico and Bali. The pendant contains a small bell-like item that emits a subtle chime when moved. It is believed that the chime has a calming effect on babies during pregnancy and after birth. The charm is often hung on long necklaces so the harmony ball is close to the belly, and is normally worn around 16-20 weeks into pregnancy when the baby begins to hear sounds. In time, the soothing jingle becomes familiar to the baby and may comfort, reassure and relax him/her while in the womb and even after birth.