I used Gelish but you can achieve the same look using CND additives in red, yellow and blue.
1. base coat and cure
2. Sleek white or cream puff and cure. ( I only did 1 coat, but 2 will make it pop more)
3. Sponge pink, yellow and blue in random areas but overlap to get orange, green and purple. Cure. Repeat if brighter color wanted. OR
3. Apply additives the same way
4 top coat and cure. DO NOT WIPE AWAY INHIBITION LAYER
5 apply black shadow or black pool very thin, you want it see through DO NOT CURE
6 apply random spots of top coat to the black with a dotting tool and allow to spread and cure. You can do one at a time and lock in place if needed
7. Apply another coat of top coat and cure. Remove inhibition layer
HTH!