Start with the source
Authenticity in oolong starts with a place, because the claims that carry the price are all about where the leaf grew.
Wuyi rock tea is defined by its site, Tieguanyin by its cultivar and method, and high mountain oolong by its altitude.
Each of those is a real, checkable thing in the trade, and each is used loosely in a listing.
Ask which one the seller means, and listen to whether the answer is a name or an adjective.
A real answer sounds like a place: a site, a village, a mountain, a garden.
A vague answer sounds like a quality claim: premium, traditional, authentic, high mountain.
Ask about the season too. Oolong is picked in spring and autumn, and the two are different teas at different prices.
Then ask who made it. A named producer is a much better sign than a named region.
Buy from shops that buy from producers rather than through brokers, which you can usually find out by asking.
The source question does not prove authenticity, but it tells you whether the seller knows.
Wuyi has a core zone of only a few square kilometres, and leaf from well outside it is still sold under the name, which is why the question is worth asking twice.
Taste as proof
Taste is the only proof you can actually hold, and in oolong it is surprisingly decisive.
A real Wuyi tea has a mineral weight and a long finish, and a forgery tastes like roasted oolong and nothing else.
Tieguanyin made the traditional way has a roasted depth and an orchid note that a modern green version lacks.
High mountain oolong is thick and sweet in the cup, and lowland tea sold under the name is thin.
Brew it five or six times. Endurance is the hardest thing to fake, because it comes from the material.
Look at the wet leaf. Whole, pliable, evenly coloured leaves mean the tea was made from decent material.
Watch how the aroma changes across steeps. A tea that smells identical every time has one note and no more.
Compare it against a tea you have verified, which is the only comparison that means anything.
Do not taste it once and decide. Three sessions on different days is a fairer test.
If the cup contradicts the label, believe the cup. That is the whole principle.
Six steeps at 6 grams per 150ml is a fair test, because a good oolong is still giving something by the fifth while a poor one stopped at the second.
Packaging and provenance
Packaging is where most authenticity claims are made, and it is the least reliable evidence you have.
A wrapper can be printed to say anything, so treat it as a claim rather than as proof.
What is worth looking for is specific information: a producer, a date, a cultivar, a batch.
A competition certificate is worth exactly as much as the competition named on it, and no more.
Geographical indication marks are real in China and enforceable there, and they are also printed on ordinary tea.
Look for a standard product code, since tea sold legally in China carries one.
Be suspicious of packaging that costs more than the tea inside it could justify.
Gift boxes are the weakest category of evidence, because the box is what is being sold.
Keep the packaging anyway. If something turns out to be wrong, it is the only record you have.
None of this proves the tea is real, and all of it can be faked. It is a filter, not a test.
A practical test
Here is a test that works: buy two versions of the same claim and drink them together.
One from a specialist, one from a general seller, at the same stated grade and price band.
Brew them side by side with the same dose, the same water and the same times, and taste blind if you can.
The differences are usually obvious once the two cups are in front of you at the same moment.
Then ask the specialist which of the two they would sell, and why.
Do this twice a year and your sense of what is real improves faster than by any other method.
Keep the notes, including which you preferred and what each one cost.
Buy small quantities while you are learning, since 25 grams is a lesson and 250 grams is a mistake.
Accept that you will be wrong sometimes. The point is to be wrong cheaply and less often.
After a year of this, most authenticity claims stop being confusing and start being obvious.
Two comparisons a year at 25 grams each is fifty grams of tea, which is a small price for a working palate.