Oldies but Goodies - December birthstones

I'll admit it, I don't really get birthstones - wait, I think I mentioned that before. There are birthstones in different cultures, there are old ones, modern ones. In fact all I remember is that as a child I was very disappointed about mine being a pearl. A pearl is not even a stone. I never quite got that one.
It's a good thing we have people at JAC who are better at that and can tell us that the Jewelry Artisans Community Oldies but Goodies Challenge will be about the colors of turquoise or blue topaz because those are December birthstones :-D
It's amazing how turquoise has taken over this challenge, but there's also one piece that shows both colors ... do you see it?

1 and 6 MC Stoneworks
2 Cat's Wire
3 and 8 Violetmoon's Corner
4 and 9 RioRita
5 and 7 Jewelry Art by Dawn