MAC Naked Dark is a darker version of MAC Naked available at MAC counters and stores. Naked Dark has a wee bit of shimmer and runs more like a NC/NW 42/43 foundation or face powder.
For myself, I would prefer to use this for as a crease or all over lid color. I wouldn't use this as a highlighter, I think it's a bit too dark for that. I'd much prefer Naked for my brow bone.
Other comparable pigments? From my stash, I picked out NYX Ultra Pearl Mania in Nude Pearl. It's really much closer to MAC Naked Pigment than it is to MAC Naked Dark. Second closest is NYX Ultra Pearl Mania in Mink, but it is much more frosty than Naked Dark.
MAC Naked Dark Pigment is definitely not an amazing bright shade with nuances of anything. It's simple and elegant. Use it anytime for something simple and let your cheeks, lashes or lips make a statement.
MAC Naked Dark Pigment and Naked Pigment retail for $23.50 CAD at MAC Pro Stores.