Selenite Crystal Balls, Satin Spar Spheres Large, Medium, Small. Satin Spar Selenite Crystal Spheres. White Selenite Crystal balls, in three sizes with stand options. Our Small Selenite Ball is 4cm wide Our Medium Selenite Sphere varies between 7 and 8cm wide. Our Large Selenite Spheres are 10-11cm wide. Please note, Selenite Crystal Spheres like this are hand crafted from Grade A, White Satin Spar Selenite Crystal. Also Note, Selenite is the crystal name for crystalized Gypsum. The name Satin Spar isnt a name, its descriptor and it means, fibrous and chatoyant, so it is describing the appearance with this type of selenite.