is that made by mixing blue with a little green? TY for your help.

Hi,
This is my first time here. I'm italian and my english is very bad! I'm sorry
I hope to help you.
You can mix cian colour with a little of yellow very slowly at time. The secret is to use based colour that you can mix to have the others.
A type of based colour are ciano, magenta and yellow and... black obviously

I use based gel colour but you can mix any type of alimentary colour

Bye!
Sara - Milan

try wilton teal, start with a little and build it up until you reach the color you like, I used it for that and loved it.

Ditto the Wilton Teal. Super easy! Just stop short of where you want the color to end up since your buttercream will darken a bit over time.