Rhotuka:
The Main collectibles, they come in lots of colors:
Red, Blue, White, Green, Brown, Black, Silver.
I could be forgeting more, but the color isn't really of significance except for the Rahaga maybe.

Kanohi
*Kualsi x 1 ("Gold")
*Pehkui x 1 ("Silver")
*Kraahkan x 1 ("Gold", Non-canonical)