Most investors tend to make a virtue out of diversification. But when the asset holder is a central bank, and the assets in question are US Treasuries, few like to shout about it. Yesterday’s curt announcement from India’s Reserve Bank that it was swapping $6.7bn of dollars for 200 tonnes of gold from the International Monetary Fund’s vaults did not mention the D-word. The exercise was described simply as “reserves management”. Move along, nothing to see.