A parallelogram in which all the edges are of equal length is called a rhombus, or a diamond.

The rhombus is often called a " diamond ", after the diamonds suit in playing cards which resembles the projection of an octahedral diamond, or a lozenge, though the former sometimes refers specifically to a rhombus with a 60° angle (which some authors call a calisson after the French sweet [ 1] —also see Polyiamond), and the latter sometimes refers specifically to a rhombus with a 45° angle.