Cork sufficient protection for aged wulong?

I got a jar of aged Dong Ding a couple of months ago. It's a bronze prize competition winner, and so it comes in it's own special jar. That jar, however, comes with a big cork (approx 4" in diameter) to seal the jar. I'm just wondering if I should trust the cork, or put it in a better container? I Googled a bit on corks, and I'm finding conflicting information; some says that cork seals airtight, and others say that it lets "just enough" air through to allow wine (for example) to breathe and age a bit.