Longjing tea of a finer Longjing is achieved only by using a genuine, slightly porous, Yixing clay teapot, which since the beginning, was popular exactly for preparing green tea well. The tea can be very expensive, and the prices depend on the varieties, of which there are many. Longjing is divided into six grades: "Superior" and then 1 down to 5. Infused leaves are a good indicator of quality, which is characterized by maturity and uniformity of the shoots harvested for processing. High quality Longjing teas produce tender, whole leaves that are uniform in appearance. Lower quality varieties may vary in color
Wuyi tea technique for stopping the oxidation process of tea, pan-firing the leaves in a dry wok rather than steaming them as had been done previously. Songluo-style green tea became popular, and the new production method spread to other regions. In the 16th century, Wuyi tea makers invited monks from Songluo to teach their techniques to them. Eventually they discovered that by allowing the tea to partially oxidize before firing, they could produce a darker, fragrant type of tea which came to be known as oolong ("wulong", "black dragon") tea. European merchants began purchasing tea in Canton (Guangzhou) during the 17th century.