Zirconium dioxide jewellery. Like diamond, cubic zirconia has a cubic crystal structure and a high index of refraction. Visually discerning a good quality cubic zirconia gem from a diamond is difficult, and most jewellers will have a thermal conductivity tester to identify cubic zirconia by its low thermal conductivity (diamond is a very good thermal conductor). This state of zirconia is commonly called "cubic zirconia", "CZ", or "zircon" by jewellers, but the last name is not chemically accurate. Zircon is actually the mineral name for naturally occurring zirconium silicate (ZrSiO). Zirconium dioxide Zirconium dioxide (), sometimes known as zirconia (not to be
Klopman diamond Klopman Diamond also appeared in a "Screaming with Binky" short, in which Binky the Clown inadvertently caused a diamond cutter to shatter the Klopman Diamond into a small pile of dust. Mark Evanier claims credit for adding references to the Klopman diamond to "Garfield and Friends". As a nod to the old animated series, the more recent series "The Garfield Show" (also written by Evanier) has also included references to the Klopman Diamond, and a crystal referred to as the Klopman Crystal is made a plot device in the direct-to-video film "Garfield's Pet Force". There is also a reference to