This was neat. I had just been sitting contemplating desaturating and wondering what effect I'd get if I used a gradient on the mask. Whaddaya know, that was one of the assignments.
I could kick myself for not having noted down the gradient I used for this one. For the border, I added a layer style using inner glow with the following settings: structure: screen, opacity 52%, b/w gradient
Elements: precise, center, 44% choke, size 27 px, contour inverted cone, range 26, jitter = 0.