I think you should use Royal blue and a little bit of black and let seat for few hours.
Black and not a purple color?
I agree that it looks like royal blue with a touch of black to darken it up a bit.
Yup...looks like a dark Navy blue..Dark royal blue with black added.
I had to make a Lapis color for my brothers wedding cake. I used purple and burgandy until I got the correct shade. HTH