Mangala sutra

A mangala sutra (from Sanskrit "mangala" "holy, auspicious", and sutra "thread") or thaali is a necklace that the groom ties around the bride's neck in the Indian subcontinent, in a ceremony called "Mangalya Dharanam" (). The necklace serves as a visual marker of status as a married woman. 
Mangala sutra's origin dates back to the 6th Century AD as a single yellow thread was tied around the bride for protection from other men and evil spirits. Mangala sutra is a social practice widespread in India, Sri Lanka, and Nepal. This practice is also an integral part of a marriage ceremony as prescribed by Manusmriti.
Overview.
Mangala sutram literally means "an auspicious thread" which is knotted around the bride's neck. It is usually a necklace with black beads strung from a black or yellow thread prepared with turmeric. Sometimes gold, white or red beads are also added to the mangala sutram, depending on regional variation. It is a symbol of marriage worn by women.
Significance.
The significance of the mangala sutra was re-iterated by Adi Shankara in his famous book Soundarya Lahari. According to Hindu tradition, the mangala sutra is worn for the long life of the husband. As told by religious customs and social expectations, married women should wear mangala sutra throughout their life as it is believed that the practice enhances the well-being of her husband.
Regional variations.
It is called, "thaali" (), "maangalyam" () in Tamil, nuptial chain in English, "thella" () in Sinhala, "mongolsutro" (মঙ্গলসূত্র) in Bengali, "mangal sutra" () in Marathi, "mangalyasutra" (), "thaali" () in Kannada, and "thaali" (), "maangalyamu" (), "mangalasutramu" () or "pustelu" () in Telugu, "thaali" () in Malayalam, Mangalasutra (ମଙ୍ଗଳସୂତ୍ର) in Odia, Konkani people (Goans, Mangaloreans, East Indians and others, including both Hindus and Christians) wear three necklaces around their necks, referred to as "dhaaremani" or "muhurtmani" (big golden bead), "mangalasutra" with one or two gold discs and "kasithaali" with gold and coral beads. In Kerala, a Christian version of the mangalsutra is called a "minnu". In Andhra Pradesh and Telangana regions, the two coin-sized gold discs are separated by 2-3 beads of different kinds. By tradition, one disc comes from the bride's family and another from the groom's side.
Designs.
Mangala sutras are made in a variety of designs. The common ones are the "Lakshmi thaali", pustelu worn by the Telugus, ela thaali or minnu worn by the Malayalees, and the "kumbha thaali" worn by the tamilians of the Kshatriya caste. The design is chosen by the groom's family according to prevalent customs. Gujaratis and Marwaris often use a diamond pendant in a gold chain which is merely ornamental in nature and is not a substitute to the mangala sutra in the traditional sense. Maharashtrians wear a pendant of two "vati" ornaments. The mangalya, thaali or mangala sutra of Kannidagas is similar to that of the Maharashtrians, except that it usually has two vatis. Nowadays many fashion conscious families opt for lighter versions, with a single vati or more contemporary style.