As we have moved to Thali from Poonool did some google got this info:
Source: Ask Agent
The "Thali" (mangalsutra) consists of two pieces, ONE FROM EACH FAMILY, traditionally dangling on a yellow thread. There are variations in the Mangalsutra and the way it is made / arranged varies from region to region.
It contains images of the Shiva Lingam - Iyers The Namam and Sudarshana Chakra - Iyengars A pair of shell (shakha) and red coral (paula) bangles - Bengali Ivory -Punjab and Rajastan Gold chain with black beads and a gold pendant - West and other parts of India. Ka****ali - gold chain with coral beads and two black beads on either side of a diamond shaped gold pendant - Karnataka, specifically "Konkini" Soft 24 Karat Gold is fashioned into necklaces modelled on the local flora and fauna—earrings like the hona, which replicate the orchid, and the lokaparo, which consists of two birds placed back to back. - Assam Gold is used to craft imitations of the human head and long funnel-shaped beads which are used in combination with shells, animal claws and teeth and precious and semi-precious stones. - Nagaland Rice grains, the Cobra’s hood, Melon and Cucumber seeds are some of the common motifs of nature inspired jewellery. - Tamil Nadu and Kerala.
Silversmiths craft large ornaments, which have a very delicate and intricate appearance. Headdresses called chak, long earrings and large nose rings with papal leaf or bird motifs are the specialties of the region. - Himachal Pradesh Turquoise, Cornelian ( sort of reddish quartz), Coral and Agate - Ladakh and East Indian States Our humble "THAALI" had a very humble Beginning. In ancient days the leaves of the palm tree called "Thaala Vriksha" were strung together and used in the place of a cord or thread. In this context, it is interesting to learn that the tying of the mangalsutra, which means auspicious thread or cord, is not a religious practice but a social one, and that too of recent origin.
It is surprising but true that this practice was not in vogue in ancient days in Hindu weddings. The "Grhyasutras" ( laws of domestic rituals) do not mention the mangalsutra but only a "kankana bandhana". The kankana bandhana or protective cord was worn by the couple to protect them from all kinds of pollution before the samvesana (consummation). It appears the mangalsutra evolved more as a popular practice than as a scriptural observance.
For Hindu women, the mangalsutra or "Thali" is the one single symbol of their wedded state. Three knots are tied - the first one by the bridegroom, the other two knots by his sister to make the bride a parts of the boy's family. The Vedic hymn recited by the bridegroom when he ties the knot, is: "This is a sacred thread. This is essential for my long life. I tie this around your neck, O maiden having many auspicious attributes! May you live happily for a hundred years (with me). ( Praying the Almighty that I be blessed with a long life ) Oh soubhaygavati.
See some Thali shapes as per the caste: (Source: Wikipedia)
Pillayar Thali
Koundar thali
Vanniyar thali
Significance of Thali:Significance
The significance to the Mangalsutra was first given by
Adi Shankara in his famous book
Soundarya Lahari. According to Hindu cultural ethos, mangalsutra symbolizes the inseparable bond between a husband and a wife. During the wedding ceremony, the bridegroom ties the mangalsutra to the neck of the bride uttering- “May you live long by wearing this sacred Mangalsutra, the reason of my life”. Married women are entitled to wear Mangalsutra throughout their life as it is believed that the practice enhances the well-being of her husband and family. It is also considered that the mangalsutra protects the marriage from any evil. Three knots symbolize three different aspects of a married woman - the first knot represents her obedience to her husband, the second to his parents and the third represents her respect for God