When I came to sponge the Ozotic it became apparent that the colours were too close and the gradient was lost, so I layered the Ozotic over the butterLONDON and had a couple of days of simple duochrome holo goodness.
On left hand I used 1x Stickey, 2x Nail Envy, 1x butterLONDON Victoriana, 1x Ozotic 533, accent nail was 1x butterLONDON All Hail the Queen topped with Ozotic 531. I reversed the main colour/accent on right hand. For extra holo I topped off with INM Northern Lights Silver Holo.
The last time I wore 533 it swung more to purple than blue, so the layering really enhanced that shade and it looed more blue, the duo nature made it look purple at times, not most of the time. Going to experiment with this again with different "underwear!"