A couple of questions (Rings/Amulets, Materia information)

[FinalBob42]

1) What are all the rings and amulets I keep finding for?

2) How do you find out what exactly materia does> Some materia only says something like "Equips Manipulate Magic". The ability list further names effects without explaining them, saying only "Manip." there.

[Dragonfire]

find a guide..... like on this site for instance

The game doesn't explain what alot of materia does, i think they were trying to make it so people could experiment and find amazing combos and such.

[mr. anderson]

rings are accsesories and armlets are armors,they dont tell you what some of the materia does because they probably want you to figure it out on your own

[Zante]

Most of the accesories will nullify some status changes or elementals, and some of them will give your characters a stat bonus.

[-N-]

Armlets are armor - Rings/Amulets are Accessories. There should be a short in-game description.

As for Materia, just equip it. I mean, Manipulate obviously has something to do with controlling things.

[FinalBob42]

Thanks. BTW, are Sources (Power source, etc.) effects permanent?

[-N-]

Yes.

[FinalBob42]

Darn, I just found mention of that. Thanks though!

[Jolts]

Yes they are.
As for the materia thing, just keep this in mind:
Green = Magic
Blue = Support (link it with green, red, and certain yellow)
Yellow = Command (adds aditional options to yor battle menu for that character)
Purple = Independant support (has special effects and doesn't need to be linked with anything)
Red = Summon