Black Crested Geckos
A black crested gecko sits at the dark end of the base colours, anywhere from deep brown to near- black. Its colour shifts as it fires up and down, so judge it from more than one photo rather than a single shot.
About the Black gene
In crested geckos, Black names a colour: a base at the dark end of the range. Keepers buy it as a colour in its own right, and as the dark ground under black-and-orange and black-and-white animals.
Appearance
Dark crested geckos run from brown to pitch black, and the darkest animals, tiger or patternless, are near-black. The colour changes from hour to hour, so the same gecko can look darker or lighter depending on whether it was fired up or down when the photo was taken. Brown holds on longest in the headstamp. It takes generations of selection to pull it out of a black animal, and plenty of dark animals still show it there.
Genetics
Listings use two names, Black and Pos Black. Black Base has its own page. Several named combos are built on black. A Halloween is a harlequin showing only orange and black; unfired it can look grey or lavender, and the black shows once it fires up. Lavender is a black base animal carrying Hypo, which pushes the dark base toward blue and purple. Charcoal and OG Black are black base Phantoms, and selection within Phantom can move the colour anywhere from pitch black to milk chocolate. Axanthic on a black base keeps the black and white, which is how a black-and-white crested gecko is made.