I think ever since I looked up this trilogy on Wikipedia and saw the table of the Circle of Twelve, I have this question, and I think the fact that the films didn't really explain what's apparently in the books doesn't help; like, besides trying to rhyme and sounding mysterious, is there actually a purpose of choosing specifically those 12 gems, animals, trees and notes those twelve time-travlers supposedly each represent?
The below is featured at the end of chapter 5 of Ruby Red, Grace Shepherd later recited it to Gwen, (shame that it didn't make it into the films) (bold parts are added to indicate the gems (not bolded in the source material))
The first pair Opal and Amber are,
Agate sings in B flat, the wolf avatar,
A duet—solutio!—with Aquamarine.
Mighty Emerald next, with the lovely Citrine.
The Carnelian twins of the Scorpio sign,
Number Eight is digestio, her stone is Jade fine.
E major’s the key of the Black Tourmaline,
Sapphire sings in F major, and bright is her sheen.
Then almost at once comes Diamond alone,
Whose sign of the lion as Leo is known.
Projectio! Time flows on, both present and past.
Ruby red is the first and is also the last.
- The secret writings of Count Saint-Germain
My first thoughts about the gems were Wikipedia:Birthstone#Zodiacal, however, not all the stones matched up; opal, aquamarine, citrine, tourmaline, and diamond, although featured as birthstones in several cultures (by month), were not if by zodiac. Amber and jade weren't listed at all. So in the end, if going with zodiacs, the only ones fitting are:
Meaning... Not even HALF of them fit... BTW, I know in the official English dubbed version of Ruby Red (film), Paul de Villiers's stone was def. not said as Black Tourmaline; I'm not sure if they've shortened it to "Tourmaline", but it didn't sound like what I've heard so I'll go check it again and see if they've changed it to fit lol.
The star sign part is a bit confusing as well, does it mean Jonathan and Timothy de Villiers are Scorpios and Gideon de Villiers is a Leo? And why only their zodiacs are specified but not the others? As of now, it just doesn't seem to be well-thought and honestly felt random.