Butter London Hen Party is one of the more unique nail polishes I've come across. Apparently it's supposed to be an "opal" shade, but to my eyes it's more a translucent eggshell colour with subtle but distinctive blueish-violet shimmer. The shimmer adds extra dimension and interest, but doesn't seem to tie in with the colour of the base. However, it's understated enough so it's not completely strange. With each coat, the neutral, beige base starts to build in opacity and the shimmer becomes more of a reflective gleam. You essentially get a very manicured and polished look, but with an unexpected twist. I've not tried this as a top coat, but I imagine it would subtly change the colour of whatever polish is under it. What I love about Hen Party is that the layers effortlessly meld together and build to a super smooth, glossy finish. For such a light colour, streakiness was kept to a minimum and wear time was truly impressive (much better than Butter London's glitter polishes, which unfailingly chip on me in 2-3 days). I took these photos when I had worn the polish for the entire week, and there was barely any difference to how it looked freshly applied.