This is a Navaratna Ring, a traditional Indian amulet. I purchased it in India about 30 years ago. The size is approximately 18mm inner diameter, equivalent to size 16 in Japanese ring sizes. Please allow for some error. Navaratna means "nine gems" in Sanskrit, and it is a combination of gems corresponding to the nine planets (Navagraha) of the cosmos. Meaning and Effects: It is believed that wearing the nine gems balances the energy of the universe, bringing health, wealth, success, and good fortune, and protecting against negative influences and obstacles. Arrangement: Traditionally, a ruby, which symbolizes the sun, is placed in the center, surrounded by the other eight gems in a specific astrological order. Gems Used: The common nine gems are as follows: Gemstone / Corresponding Celestial Body Ruby / Sun Pearl / Moon Red Coral / Mars Emerald / Mercury Yellow Sapphire / Jupiter Diamond / Venus Blue Sapphire / Saturn Hessonite Garnet / Rahu (Ascending Node) Cat's Eye / Ketu (Descending Node) There is no guarantee of the authenticity of the stones used.