Only the smallest and brightest, with two pointers aimed at the head of the cross, is the true cross. The brightest star (alpha Crucis) is at the foot of the true cross. The pointers lie to the east.
The diamond cross has no pointers and is fainter than the other two. The head of the diamond cross is just below (south of) a very bright part of the milky way, which includes numerous star clusters and the amazing eta carina nebula. Many clusters and the nebula are visible in binoculars. The head of the diamond cross (theta carina) is actually in a star cluster, which makes the head look fuzzy to the naked eye. In binoculars you can see many of the cluster stars around theta carina. (Carina star field image)
The false cross has two pointers, but they point to the brightest star, at the foot of the cross. Also they point from the west, not the east.
Remember - the crosses can be any way up as they circle the south pole. The photographs and diagrams show the crosses as seen in June / July, when they are highest in the sky during the evening.
