A silver or gold chrysanthemum with large, brightly colored stars at the tips. The name comes from the Latin word for "jewel".  A diadem shells displays both a tail and color at the same time. This requires the use of special stars such as married or tipped comets. In practice most (pseudo-) diadem effects are achived using common colored stars with excess metal fuel, e.g. excess ferrotitanium, which also produces an elegant tail in conjunction with a colored head.