I know of only one person on this forum that has one... I have not heard of any updates on any Black Pearl projects... I am very interested to see how these are coming along...
I wouldn't say "rarest" for all we know there could be hundreds of wild geckos out there carrying the genes and we just haven't found out how to bring out those genes yet...
But in the event of them being a newly discovered morph, with few currently exsisting morphs available to the public, yes they would be one of the rarest currently.... But the way morphs are allways changing and being discovered its only a matter of time before the next best thing pops up...