I used to do this quite a bit when I was younger, adding crushed eyeshadow and glitter and I ruined many a nail varnish in the process! I knew what I wanted to achieve, make this a deeper, maybe a tealy green. I decided that if I added a deep blue it might turn out they way I wanted... It didn't! But, what I got was much nicer and very unexpected, making it possibly even better.
I added this E.L.F. polish in Dark Navy to the Claire's to get the colour I was hoping to achieve... But here's what i actually ended up with!
This was the most unusual colour, a kind of inky, creamy, greyed out blue-green with a tiny hint of shimmer. (How many more adjectives can I use to describe it I wonder!)This picture doesn't actually do this colour justice... In different lights this flashed green, slate, even grey at some points. Success, albeit unexpected!