Ceylon is known, on the whole, for tea which has undergone the process which produces black tea (that is, fully oxidized). In recent years, the tea factories and tea estates have experimented with the production of Oolong and Green teas which are simply a style or process. Both the estates and factories had to gain the experience necessary to produce these styles of tea since Oolong and Green processed tea were primarily the domain of China and thus also the manufacturing know-how or experience. As the Tea factory masters gained experience in the manufacture of Green-processed tea, their expertise improved dramatically. Therefore, in Sri Lanka during the first years samples of green teas were rejected because they (the tea masters) did not have the necessary expertise. However the investment in time and effort in learning the new process was well worth in that now a Ceylon Green from the Central Highlands pluck produces the very finest of the Ceylon Tea.