I had only read about these and knew some of the factories in other parts of the world needed one. Imagine our surprise to find that every facility we visited in China had one. These are coveted machines and state-of-the-art. They separate stem and stalk from leaf and remove foreign material and particles of all kind. All over the world, tea is priced and valued for uniformity of grade and here is a fool-proof way of achieving it. Color Sorters come in all sizes and capabilities and the mechanism is simple - put in unsorted graded leaf at one end and have it come out the other end through various chutes calibrated to catch different size and color parameters. This is obviously not done for high-grade specialty tea but definitely for the mass-produced teas such as Keemun, Gunpowder or Chunmee. A tea such as Pai Mu Tan would be wholly unsuitable for such a machine.