If admin's list is complete, and I'm assuming that it is, then there have been eleven colors offered from the factory.
Three RS colors.
Four colors that end in "Pearl".
Two that end in "Metallic".
And the other two.
In law school, if you want to avoid flunking out, and if you'd like to pass the bar exam, you learn all kinds of weird ways to memorize lists of things real fast. I would lump them into sub-groups. Some people use mnenomics: in other words, make a sentence that uses words that start with the first letter of every color, in this case.
E.g.: to remember "Hot Lava", "Solar Yellow" and "Envy Green", I would make a sentence like, "Hubbard Simplifies Everything."
Except that I hated mnenomics and they drove me crazy. But some people swear by them for memorization.