That is the result of spontaneous mutation: a sudden change in the plant’s genetic material whereby the property of ‘colour’ changed from green to dark. Spontaneous mutations are rare, particularly a mutation that is stable and does not revert back to the original colour. Zamioculcas Raven was discovered in South Korea, and was successfully tested there for stability over a number of years and ultimately introduced as a new variety in the Zamioculcas family. Because Raven is so dark, it is particularly remarkable that the new shoots start bright green and gradually change colour to the darker shade. That natural colour change is therefore in the plant’s DNA, and is a very exceptional process to behold. The young green shoots do need some time to darken, between 5 and 10 weeks depending on the period and light strength.