From Leopard Gecko Wiki
The Black Pearl morph is currently in its developement stages. The European breeder, Living Art Geckos and Asko Kampinga have been working on the project. According to their site, the Black Pearls first appeared at a Dutch zoo which had received a shipment of Leopard Geckos from the wild. In 2006, Living Art Geckos and Asko Kaminga received some Black Pearls. As of right now, they and the Black Velvets are the closest geckos the Leopard Gecko Community has to Melanistic Leopard Geckos.
The Urban Gecko bought a set of Black pearl geckos (from an unknown breeder) which they immediately bred in hopes that they would be able to produce there own black pearls recieved from another breeder (unknown breeder), the results were Awful! All the babies were mack snows, in short the "black pearls" were hoax's, which is know today as one of the biggest reptile scams in history.