A lot of the tea companies that have British-style teas, which also sell oolongs, tend to carry a series of oolongs from Taiwan that they label only as "Formosa Oolong". They tend to have a dark color, and range from different grades, with some of the higher grades often being labelled things like "Champagne Oolong".
What exactly are these? Are these all Oriental Beauty (Dong Fang Mei Ren) or Bai Hao oolongs, and just different grades of them? Or are they something else, and not always Bai Hao?