Here you have 4 purple polishes from Models Own, 3 of them are however retired/discontinued:
Deep Purple is a retired duochrome blackened purple with a shift to lighter purple and a hint of a dark teal leaning green. It is very opaque in 1 coat, but this is 2 without a top coat.
Purple Imperial is still available; it comes from the Kaleidoscope collection. It’s a mid purple with a very shiny, kind of metallic finish. This is 2 coats, no top coat.
Purple Mystique is a retired dark royal purple shimmer, maybe not unique, but always very pretty. It is very opaque in 1 coat, but this is 2 without a top coat.
Purple Passion is a retired red toned magenta leaning purple with a semi matte rubber finish. 2 coats would be enough for normal use, but this is 3 coats without a top coat.