Buy what China takes, sell what it makes. Follow this rule over the last decade and big bucks would have come from bull markets in high quality iron ore and copper. Zinc and aluminium, of which China has plenty, did not perform nearly as well. This year, though, the maxim did not hold. Zinc and aluminium have helped lead the CRB Base Metals index up 12 per cent this year, its best performance in a decade. If prices rise high enough for the latter, China may simply increase exports, capping the rally.

So far this year, three of the top 10 performing constituents of the MSCI World Metals and Mining Index have been aluminium related. These include Alcoa, up 56 per cent versus just 4 per cent for the benchmark. Despite supply bottlenecks created by forward sellers, China has all the aluminium it needs. Excess supply in China this year will be the largest since at least 2000, and net exports have steadily risen for two years.

As for zinc, Citi points out that China holds nearly a fifth of world reserves. Soft demand has led to mine output falling on an annual basis for the first time in four years. Not only do the Chinese consume 45 per cent of the world’s zinc (and half of the aluminium), but a third of it goes to construction there. Zinc galvanised steel product inventories used in construction touched record highs this year. Yet the zinc price charges on, and the shares of Sweden’s Lundin Mining, which has the fourth largest zinc reserves, have soared 38 per cent this year.