I add the colors along with fragrance. I don't have a lot of different colors so I mix dyes to get the colors I want. I have some brights, don't consider them fluorescent.
I mixed yellow and honey dew green to get the lime. The orange is red & yellow. The one by orange is a bright coral. I got it by putting in more dye and adding a drop of burgandy, it's the same dye as the light pink one. I don't have a purple so I mixed blue and pink. I only have 6 dyes: red, green, yellow, blue, burgandy & coral. The dark burgandy is Mississippi State University color maroon and I added a lot of burgandy with just a few drops of blue to get it that color. I just mix and add as I go along watching the colors develop, no exact formula. I've been selling in sachets mostly but made a few aromies.
NOTE: From what I've read, you can only use candle dyes. I've only used liquid dyes so far. RE has 45 dyes.
https://rusticescentuals.com/colorant-candle-dye-liquid/