The size of tea particles (known as the grade of tea) has no bearing on quality, and only influences strength. When we harvest tea leaves and make them into tea, we use the traditional, artisanal method – withering, rolling, and in the case of black tea fermenting and baking the leaf. While rolling, the leaf can become elongated and wiry, tightly curled or smaller particles which come out as OPA, Pekoe, BOP or finer Dust or Fannings grades. A single batch of good leaf can yield several of these grades and whilst they would all be good, the only difference in the size of particles would be the strength. That is related to the surface area of the leaf when brewed with hot water. A teaspoonful of Dust tea can have four times or larger surface area than the equivalent quantity of OPA, and hence offer better extraction, and thicker, stronger brew.