Most zircon deposits come from Burma, though Australia boasts the oldest deposits dating back more over 4.4 billion years.Other notable sources include Brazil, Korea, Madagascar, Mozambique, Nigeria, Tanzania, Thailand and Vietnam.Of course, the two are completely different - cubic zirconia (CZ), is a lab-created synthetic material, while zircon is a naturally occurring gemstone with a very different chemical composition.
Blue zircon is actually produced by heating more commonly occurring brown zircon.
However, only some brown materials have the appropriate physical structure to turn blue when heated, typically only deposits found in South East Asia - which is why most blue zircon comes from Cambodia or Burma.
Green zircon is very rare and owes its color to minute natural traces of uranium and thorium. Zircon belongs to the large group of minerals known as neosilicates that contain both silicon and oxygen in their composition.
The neosilicate group includes varieties of beryl and garnet, andalusite, kyanite, olivine (peridot), tanzanite, topaz, tourmaline and quartz.
Green zircon is rarely seen in the gem trade and is highly sought after. An unusual trait with zircon is that its gemological properties exhibit very wide ranges, such as hardness ratings spanning from 6.5 to 7.5 on the Mohs scale.