As per Hindu Dharma, Mangalsutra is an ornament of a woman denoting her marital status; it symbolizes the inseparable bond between a husband and a wife. Each groom prepares a Mangalsutra for the bride as per his capacity If it is not possible to make a Mangalsutra with gold or silver, it is made by stringing black beads in a thread.
In the center of the Mangalsutra are two cups. Round shape is associated with the Sattva Guna in the form of Shiva-Shakti. The central point of the round shape provides waves in the form of striking Shakti (Energy) whereas the raised part is associated with Brahman in the form of Shiva This is believed to regularize a women’s blood circulation.
This is also said to control the body pressure levels to the maximum extent. Because of the constant friction of the metal touching the body directly, the effect will be more to gain the said benefits. The black color of the beads is said to provide protection and absorb all negative vibrations before they affect the bride.