Copper sulfate pentahydrate in the form of large crystals of more than 1 cm diameter and copper sulfate in the form of small crystals. The small crystals have a lighter color, due to scattering of the light in the somewhat transparent crystals. There also is an anhydrous form of copper sulfate, which easily becomes hydrated again and which is totally different.

Copper sulfate can easily be crystallized from its aqueous solution, giving beautiful large deep blue crystals. The picture below shows some shiny homemade crystals, the larger ones have a size of around 3 cm.