In appearance, diopside may be confused with peridot, demantoid, zircon, enstatite, grossularite, tourmaline, chrysoberyl, or grossularite. Diopside has perfect cleavage and is somewhat difficult to facet.
Diopside has several varieties, including a chromium-rich gem variety called chrome diopside. Violan is rare blue variety found in some localities in Italy. There is also a green "cat's eye" variety that contains minute inclusions, probably of rutile, that reflect light in such a way as to produce a lively linear luminscence within the crystal. Still another variety is quite dark, with included rutile needles aligned so as to produce a 4-rayed star, hence the name star diopside. Ordinary diopside is typically white or green and can have a nice glassy luster. While the color of chrome diopside is much brighter, many specimens of ordinary diopside are also cut for gemstones. Mineral specimens of diopside can be very striking in appearance, and of interest to mineral collectors.