I'm making DH a lego brick birthday cake and my mum some fancy fairy cakes for her birthday. I sent DH to the cake shop to get some colours and he came back with crimson and Christmas red. he said the lady told him one came out pink, but couldn't remember which.
Either one will if you only put a tiny amount in, and I'd use the crimson as it's less intense. You literally only need a teeny amount of those paste colours - I dip a toothpik in, then dip it in the icing
Christmas red has a more pink tinge to it than crimson, but as CMOT says, you only need a tiny amount. Once its thoroughly blended, leave it to rest for a few hours as the colour does deepen over time. As a warning, you need a lot of red to get rid of the pink undertone, so if only blend as much as you need