Commodore sold different versions of the black monitor. The first (I think) version was black plastics and the front panel was black. In the later days (or maybe in between) this version was sold out and they colored the "normal" beige 1084. The front panel was left beige (I assume it was to complicated/expensive to paint it black).
The colored version is even more uncommon than the real black ones. Uglier than the real ones, but not that common.
