I listed the colors of each soul stone in a previous thread here they are.

Paladin: Pale Blue
Monk: Yellow
Warrior: Red
Dragoon: Blue (slightly lighter than Scholar)
Bard: Chartreuse
Ninja: Dark Purple
Dark Knight: Burgundy
Machinist: Cyan
White Mage: White/Ecru
Black Mage: Purple
Summoner: Green
Scholar: Blue (slightly darker than Dragoon)
Astrologian: Orange

I thinm they all match except DRK, and possibly Machinist, but I havent run with any machinists, so I cant say for sure.