The Black Palace Blaster is one of the rarest figure accessories. Originals should float in water but more modern repro items can sometimes also be found to float. 

Many repros do not have the circular dimple on the handle. There is also a circular bump on the barrel that repros are often missing. In some cases repros will have a circular dimple on the handle but not on the barrel so these two things are easy to look for.

Many of the repros are made with a more brittle plastic or with an incorrect colour. A sound test can be conducted by dropping the weapon carefully onto a hard surface. Repro items make a different sound when compared to original items.