Similar to this decoration, it`s black french gel polish.
I used Bluesky gel polish 518 for the french and Bluesky 504 for the base.
On some of the nails I painted black lace above the french using black acrylic paint.
On the index nails I sticked a nail jewel- butterfly with multicoloured rhinestones.
Finished the nails with Bluesky gel polish top coat.