The trap to know
The trap with oolong is that the category is so wide a name tells you almost nothing about what is in the bag.
Oolong runs from about 15 percent oxidation to about 70, from unroasted to heavily charcoal roasted, and from a few pounds a kilo to several hundred.
The usual version of the trap is paying a high price for a tea described only as oolong, which is a description with no content in it.
The second version is buying a famous name at a price that cannot possibly be real.
Tieguanyin and Da Hong Pao are the two names used this way most often, and both are produced in quantities far smaller than the market in them.
What protects you is knowing which three things actually set the price.
A third version of the trap is buying a roasted oolong when you wanted a light one, because roasting hides what the leaf really is.
Knowing which end of the range you prefer before you shop is the cheapest protection there is, and it costs one tasting session.
Check the grade claim
Three things set an oolong’s price: altitude, cultivar and roast. Everything else is decoration.
Altitude is the big one for the Taiwanese high mountain oolongs. Above about 1000 metres the leaf grows slower, and above 1500 it is genuinely scarce.
A tea sold as Alishan or Lishan should name the mountain and the altitude. If it says only high mountain, it is probably from lower down.
Cultivar matters too. Qingxin is the standard for high mountain oolong, and Jinxuan is the milky one. Both are legitimate, and neither should be sold unnamed.
For roasted oolongs such as Da Hong Pao, the question is whether it is a blend or a single cultivar. Most of what is sold is a blend, which is fine at the right price.
A charcoal roast should be described by how many times it was roasted and when. A seller who cannot say has not been paying attention.
Harvest season is worth asking about too. Spring and winter pickings are the prized ones, and summer leaf is cheaper for a reason.
Winter oolongs are scarce and expensive, and a winter tea at a spring price is a spring tea.
Smell before you pay
Smell tells you the roast level immediately, which is half of what you need to know.
A light oolong smells floral, sometimes of orchid or fresh butter, and should have no toast in it at all.
A medium roast smells of caramel and baked fruit, and a heavy charcoal roast smells of wood smoke and dark sugar.
A burnt or harsh smell means the roast was rushed or pushed too far, and it will not come out in the cup.
A green, grassy smell on a tea sold as roasted means it was never roasted properly, or was roasted once and sold as if it had been done three times.
Ask for the wet leaf after brewing. The aroma on the lid tells you more than the liquor does at that point.
Smell also tells you whether a tea has been refreshed. A re-roasted oolong smells of toast with little underneath, because the aroma has already gone.
A good light oolong smells stronger wet than dry. If the wet leaf has less aroma than the dry leaf did, the tea is old.
Trust storage over label
Roasted oolong keeps better than most people think, and light oolong keeps worse.
A light, unroasted oolong should be sealed and refrigerated, and drunk within about 18 months.
A well roasted oolong will hold for several years at room temperature if it is sealed, and some are better at 3 years than at 1.
The failure mode is a light oolong stored warm and open. It goes flat, then stale, and re-roasting it is the standard fix.
A re-roasted oolong is not a fake, but it should be sold as what it is. Ask whether it has been refreshed.
Buy roasted oolong in larger quantity and light oolong in small. That one habit avoids most storage problems in this category.
Vacuum sealing suits light oolong well, and it is worth checking that the bag is still tight when it arrives.
Roasted oolong in a paper bag inside a tin is the traditional answer and it works. Avoid anything kept loose in a drawer.