Heavy metal overload...charcoal metallic shimmer polish, chrome powder, and metal accents. It may sound like a lot, but the mono-"chrome" (see what I did there) color pallet makes it a cool, cohesive look.
Apply a grey metallic shimmer polish.
Apply a no-wipe gel top coat to the pinky and cure. Use a sponge brush to rub silver chrome powder over the entire nail. Apply another layer of top coat and cure.
Apply metal chrome accents to the middle, ring finger, and thumb. Working one nail at a time, apply a no-wipe gel top coat. BEFORE curing, place the metal accents in the desired position, and then cure. Apply another layer of top coat to really secure everything, and cure.