The contact angles of water and formamide droplets on two different ruby crystals grown from MoO3 flux were measured. The specific surface free energies of the (11 (2) over bar3), (10 (1) over bar3), and (0001) faces were calculated using the Fowkes approximation and compared with the length of the normal lines from the center to the crystal faces. The relationship between the specific surface free energy and the morphology of each crystal is found to satisfy Wulff's relationship. (c) 2007 Elsevier B.V. All rights reserved.