So, three-month copper closes overnight at $US7416/t. Hard to believe it was at $6800 just four trading sessions ago.

The metals were helped by really encouraging numbers out of Germany, where industrial production seemingly surged in April, but more so because of some impressive import-export statistics out of China, although even usually neutral or reserved market charters were voicing doubts about the accuracy and reliability of the figures. As one chartist put it, Chinese exporters may be over-invoicing to circumvent government capital controls.

In fact, if you believe it is the bellwether commodity, the details about copper will give you pause: Chinese imports of the red metal in April were down 24% year on year (7% month on month). Gold had a good spike overnight, too, and the commentaries were attributing this largely to the good data out of China.

But what if the data is wrong? Seriously wrong, and that China is not heading for a “subdued” 7% growth rate - one which metals exporters probably believe they could live with - but closer to 3%?

China, after all, is all set to overtake the US economy in the near future; some say as early as 2017.

But there was a disconcerting headline in London’s Daily Telegraph overnight proposing that “China may not overtake America this century after all”, and arguing that the country’s 30-year miracle is nearing exhaustion.

Now, this writer, who remembers all the astonishing economic figures out of the Soviet Union in the 1960s, has for a long time been highly sceptical about Chinese statistics. Of course, the spectacular growth has been there for all to see. Just fly into Shanghai, or note the number of industries (aluminium smelting, manufacturing) in which China is the top dog.

But, as I have harped on about, we have so many commodities influenced by a dominating buyer about whom we have no real reliable information. We don’t know the size of the commodity stockpiles - of copper, for example. How can miners make decisions when they don’t really know what their prime customer is up to?

We’ve mentioned over-invoicing. What about multiple collateralising? That’s when a Chinese company uses one metal stockpile to raise multiple loans, with the lenders thinking they alone have control over the collateral.

Then there's shadow banking. This week JP Morgan Chase estimated the Chinese shadow banking system at $5.86 trillion, or equivalent to 69% of China’s GDP. The bank’s chief China economist Haibin Zhu sees the rapid growth of the shadow banking as a trigger for systemic risk (a view also recently expressed by Glenn Stevens at the RBA). But Zhu also makes the point that there is no clear definition of what makes up shadow banking. Apparently, even the Chinese authorities don’t really know. And he makes the point that the shadow banks face serious serious default risks (not just from some idiots who have borrowed a few quid to buy a wide-screen TV as one might expect - my interposition) but big money loaned to local governments and real estate developers.

But back to that Daily Telegraph story.

Ambrose Evans-Pritchard starts his report citing the plan to build the world’s tallest tower, a 220-floor edifice in Changsha. It was meant to be completed in March. The ground has not even been touched. He sees this as a sign that even China is now starting to realise its limits.

He quotes a cable released by WikiLeaks from the now new Prime Minister Li Keqiang in which he described Chinese statistics as “man-made”. US intelligence believes electricity consumption figures have been fiddled to make growth look greater than it has been.

He also quotes the US Conference Board projection that Chinese growth will average 3.7% from 2019 as the ageing population crisis hits, and Michael Pettis, of the Guanghua School of Management at Peking University (yes, it kept the old name), seeing growth of under 4% over the next decade.

Chinese domestic levels are at 200% of GDP (for comparison, so-called debt-trapped Spain’s are at “only” 125%). Total credit has jumped from $9 trillion to $23 trillion in the space of four years.

Trouble waiting to happen?

The good news is that the government in Beijing is aware of the bubble danger, and is trying to curb speculative activity across a range of sectors.

But the warning signs are there.

Something to keep in mind seeing so many Australian companies have so many of their eggs in the China basket.