Tea is an evergreen plant that is indigenous to China and some regions of India. The word tea refers to both the plant itself and also to the infusion resulting from steeping in hot water. Women hand harvest the tea leaves and submit for size sorting and grading. Leaves are oxidized, fired, and sorted by passing them over vibrating screens of different mesh sizes to produce grades with even sized particles. Grading of tea refers to the leaf size and location of the leaf on the tea bush. It does not refer to flavor or quality of the tea. There are approximately fifteen hundred varieties of teas and nine grades of teas. Tea grading is not standardized between countries and the terminology may vary for green, black,and oolong teas, which are the three most popular varieties in the western world.
Following is a summary of each of the nine tea grades. Grades D and F refer to small particles and small broken leaves, remants from the sorting and crushing process, that are primarily used for tea bags. Dust and fannings make a particularly strong brew when placed in tea bags. Souchong tea is the largest leaf, closest to the bottom of the branch. It is a coarse leaf and that is why Souchong leaves are ideal for use for smoked teas, which are tea leaves processed with chemical compounds and smoke dryed that give it it's smoky aroma and flavor.
The remainder of the tea grades have to do with pekoe which is a small fine leaf found in black tea. Pekoe(P) is a small and less coarse leaf. Orange Pekoe (OP) leaves are found near the end of the branch, are the youngest, and smallest leaves on the bush. BOP, or broken orange pekoe grade refers to leaves that are purposely broken by machines to increase the infusion speed. Flowery orange pekoe (FOP) is a black tea that contains leaves and leaf buds or tips. Adding on to that is FBOP which refers to broken leaves with tips.
Some flowers on black tea plants are golden in color and tea is graded for that also. Golden flowery orange pekoe tea (GFOP) contains golden colored flowers and tips. The dark leaves have golden ends, or tips that are highly prized. An increased amount of golden tips are included in a grade called tippy golden flowery orange pekoe (TGFOP). The term tippy means an abundance of tips. The finest grade is FTGFOP, or finest tippy golden flowery orange pekoe. This grade is comprised of the very best golden flowers, leaf buds, and the youngest leaves.
Tea grading, as summarized here, represents the grading system for black teas. There are grading systems for other varieties of teas as well as for crushed teas, et al. While FTGFOP is the finest grade of black tea, that same content may be found in the dust and fannings of the common tea bag.