Finding a blue purple - like a tanzanite colour - in the world of soft glass is a rare thing. Red purple like amethyst - no problem - a dime a dozen. Blue purple, not so much.
I wanted to compare 039 Dark Violet, 041 Light Violet, and 058 Ink Blue. The verdict? Dark and Light Violet are in the red purple category, and Ink Blue is a ... well - you can argue that is it a blue, or a slightly warmed up blue.
Black base, white dots - then from the left, 039, a row of 041, and 058 on the right. Then mashed.
Ink Blue is just a little warmer, just a hint travelling towards purple, than a true blue, but is doesn't really hit the mark of tanzanite.
I think the violets are prettier than, say Effetre 042 or 044 transparent purple, but I may have a pre-existing bias about those colours. ;-)