Ring of fire, Ring of Air, Ring of ?

[Gordis]

Originally Posted by Hookbill the Goomba

Slight correction;

LOL.

I am no expert on old philosophies. You better google "Four elements" and "Five elements" to learn much more.
I gather Tolkien mostly took into account the European (originally Greek) tradition of Air, Water, Fire, Earth and Aether. Especially considering that the Roman Catholic Church backed it. Japanese-Chinese beliefs were more alien to him, I guess.

As for the stones, it is stated (somewhere) that Nenya had an adamant, Narya a ruby and Vilya a sapphire. Nenya was made of mithril, the rest of gold. Every one of the Seven and the Nine had its own stone, but we are not told which ones.