The well-known apple-green glaze is composite in nature, consisting of a high-fired, stone-colored crackled glaze that has been given a coating of translucent emerald green and re-fired at a lower temperature. Some authorities feel that this group of monochromes was introduced during the Kangxi reign; however, most of these wares seem to date to somewhat later than the Kangxi period.
The "apple green" color is derived from copper. It is a transparent glaze applied over a ge-type crackled base. Sometimes the underlying craquelure is also tinted black, brown or yellow in coherence with the practice of the true ge-ware.
The apple green enamel had been used previously but never as an overall monochrome glaze on top of a crackled one until the Kangxi period. Thus it was a new innovation of the period.
The Kangxi apple green was mostly of a pale tone while the 19th century and later apple green wares usually are much darker, of different tonality and more brilliant green.
The origin of the apple green glaze was most likely a product of the Lang kiln famous for the langyao red (sang de boeuf) glaze making its appearance around the same time and basically look very similar. Both are copper based translucent glazes applied over a crackled base though differ in the kiln firing procedure.
Generally those pieces with an iron wash on the rim date no earlier than the Qianlong period. The rekindled interest of archaism from that period is reflected by this trait simulating the appearance of Song guan and ge wares as well as Song influence in shapes and forms.