Black Beauty is a mutation from Colocasia 'Illustris'.  As you can see the leaves are much darker.  They still tend to fade in full sun to look very close to 'Illustris' and it is very easy to get the two confused.

 

This is a picture of one grown in mostly shade.  The new leaves are so dark and almost have a purple velvet color to them.

 

I would recommend to give this elephant ear part sun and as much water as you can or want to give it.  Black Beauty can and will grow directly in a pond during the summer.