what colors do you mix together to make tiffany blue?

Here are two forum links about that. Hope they help.
http://cakecentral.com/cake-decorating-ftopict-711716-tiffany.html+blue
http://cakecentral.com/cake-decorating-ftopict-720374-tiffany.html+blue

I did a tiffany blue for my stepdaughter Tiffany's birthday. I believe the color I used was turquoise ( by americolor ). It been a while since I done this cake. But, I'm pretty sure that is what I used. There is a pix of it in my photos

Honestly, the Betty Crocker neon blue is almost a perfect match to the "Tiffany" blue. I stumbled across this when it was 2 AM and the grocery store was the only thing open. good luck!