Hi ‘Manila’,
I am happy that you posted the question here at Tea Guardian. I know this is very confusing. Tea categorisation really should be easier to understand. I shall talk to Leo about this same question which has been asked a few times before you did. Hopefully he will write more to clarify that.
As for why Oriental Beauty is an oolong, it is really a complete oolong process and beyond. The oxidation in our selection is deeper than some others but not unusual. A complete oolong process is composed of withering under the sun, shading to regain water, rattling the leaves before oxidation, repeating the process, killing green, rolling, resting and baking dry. In black tea processing, such as that for Imperial Topaz from the Himalayas, the oolong steps are omitted and only the shorter black tea steps make the tea. You can see the comparison in Leo’s articles in:
The degree of oxidation in black tea production varies from very light, like in Himalayan Finest Flowery, or some Darjeeling, to very thorough, like in Red Plum Classic or Dianhong Golden.
So the process determines the category, not the degree of oxidation.
Hopefully that clarifies it and you enjoy either tea without the puzzle!
