I mentioned the Da Vinci 2 a few posts ago, causing some confusion, as I neglected to mention that it was the Opaque Da Vinci. There is a transparent Da Vinci as well. It comes in varying degrees of transparency.
You can see that the completely clear rod to the left develops to a light yellow with streaks, (the bead on the left was reduced - and went darker.)
Whereas, this rod, barely visible behind, is already streaky yellow, and the colour in the glass develops to be much darker. There is a lot of color variation - from smokey blues to dark amber. Because it's so dark, I suggest that this would look best in thin layers over clear.