I'm not... entirely certain now that I think on it, but I believe it means which of the Twelve you were born under.
You see, each of the months are also tied to one of the twelve gods of Eorzea. The first month is Halone's, the second is Menphina's, and so on. And so whichever month your character was born correlates to which deity is your "guardian deity." And each of them have a symbol that correlates to them... so I figure that when they say the zodiac they mean that.
So that means if your Dunesfolk was born in... say, the Third Umbral Moon (sixth month, roughly our June), then the symbol on their gem would be Oschon's. Then again, it could just be whichever deity you or your family has as their "primary" diety and not be tied to date of birth at all... I suppose you could work it either way, really.
Um, I hope that helps! ... and I also hope that someone comes and corrects me if I'm way off base on this.
You see, each of the months are also tied to one of the twelve gods of Eorzea. The first month is Halone's, the second is Menphina's, and so on. And so whichever month your character was born correlates to which deity is your "guardian deity." And each of them have a symbol that correlates to them... so I figure that when they say the zodiac they mean that.
So that means if your Dunesfolk was born in... say, the Third Umbral Moon (sixth month, roughly our June), then the symbol on their gem would be Oschon's. Then again, it could just be whichever deity you or your family has as their "primary" diety and not be tied to date of birth at all... I suppose you could work it either way, really.
Um, I hope that helps! ... and I also hope that someone comes and corrects me if I'm way off base on this.
~