Jade is one of the most misunderstood gemstones. It is actually two separate materials: jadeite and nephrite. Together, these materials have more simulants than most other gems. Thus, it is important to know the various simulants, and to understand how to separate them from jade. This article examines the key identifying properties of green jade (jadeite and nephrite) and contrasts them with the properties of the 10 most common green jade simulants. Simple visual techniques are emphasized as well as the appropriate gemological tests. -- AATA