Polki jewelry :
Introduced by the Moghuls, Polki uses natural unfinished diamonds. The diamonds are flat or uncut in its natural shape and set on 24 carat gold.
The technique used to make polki jewels is called “Jadau”. Lac and fine pure gold foils are used with this technique. Gold foil is placed at the back to bring the diamonds together. Holes are cut for the diamonds. Then, when the diamonds are to be set, a natural glue (resine) called “lac” is inserted in the back and is visible through the holes. Polki can also uses gemstones (sapphires, rubies, emeralds…). It is more expensive than Kundan.
Kundan jewelry :
From Rajasthan, Kundan jewels use glass imitations, not real diamonds. The technique used to make Kundan is the same as Polki : Jadau. It can also uses precious or fine gemstones (sapphires, rubies, emeralds…). It is less expensive than Polki.
Meenakari jewelry :
Meenakari refers to the enamel work done on a metal surface. It is namely used on the reverse side of Kundan and Polki jewels. The word “Meenakari” means “art of enameling” (Meena = enamel ; kari = art).
Navratna jewelry :
Derived from the Sanskrit word meaning “nine gems”, Navratna jewelry refers to jewels created with nine specific gems : diamond, ruby, emerald, coral, pearl, yellow sapphire, blue sapphire, hessonite and cat’s eye.
Each gemstone has a celestial significance : Ruby for Surya (Sun), Pearl for Chandra (Moon), Red Coral for Mangala (Mars), Emerald for Budha (Mercury), Yellow sapphire for Brihaspati (Jupiter), Diamond for Shukra (Venus), Blue sapphire for Shani (Saturn), Hessonite for Rahu (the ascending lunar node) and Cat’s Eye for Ketu (the descending lunar node).
Navaratna Jewelry was worn by the kings and the Maharajas as an amulet. They believed that the combination of these nine gemstones invoked the cosmic powers.
Moghul jewelry :
The Mughal dynasty was a Muslin dynasty of turkic-Mongol origin that ruled most of northen India from 1526 to 1748. The Mughals who came from Central Asia brought with them techniques of gem-setting. The Mughal emperors used jewelry to show their power. Decrees limited the wearing of jewelry to the ruling classes. It was the Golden age of Indian jewelry.
Sources : http://www.myweddingplanning.in/drool-worthy-ideas-101-wanted-know-kundan-polki-jadau-jewellery ; http://english.fashion101.in/news/FAS-FSPO-difference-in-polki-and-kundan-jewellery-4983878.html ; http://www.culturalindia.net/jewellery/types/navratna-jewelry.html ; http://blog.jewelsutra.com/2009/04/kundan-polki-and-meenakari.html https://global.britannica.com/topic/Mughal-dynasty and https://theculturetrip.com/asia/india/articles/mughals-myth-and-murder-500-years-of-indian-jewelry/