I was trying to blend blues to match a swatch. I started with sky blue and added navy, the color is really off. It needs to be darker, more like a royal.

Can I just add more royal or do I need to start over? Any suggestions on achieving a nice bright royal blue, that one always gives me problems.

TIA!

Some colors deepen over time, stop adding for an couple hours (if you have the time) and check it again. Do you have "royal" blue coloring? You said "should I add more royal?" but, you said you started with sky and navy. Unless the fabric you're trying to match is going to be right next to the cake; don't be so concerned about a PERFECT match.