From Leopard Gecko Wiki
Hyper Melanistics are Leopard Geckos that display more dark pigmentation (also known as melanin), and therefore have a darker appearance than most other Leopard Geckos. [[Hyper Melanistic} Leopard Geckos are not completely black. A solid black Leopard Gecko would be considered Melanistic. Some examples of Melanistic Leopard Geckos are Black Velvet and Black Pearl.