"A century of first-hand experience in the art of managing markets is helping diamond producers accomplish what the rest of the mining industry has been unable to during the commodity collapse: shut down supply," writes Thomas Biesheuvel for Bloomberg Business. With rough diamond prices dropping 18 percent last year, world supply was reduced by a quarter as the biggest producers, De Beers and Alrosa, cut output and sales. That compares with the situation in commodities such as iron ore and copper, "where companies like Rio Tinto Group and BHP Billiton Ltd. spent billions on expansions over the previous decade and were reluctant to respond to surpluses even during prolonged bear markets."
The moves by De Beers and Alrosa to cut supply last year prevented an even bigger meltdown, according to RBC Capital Markets analyst Des Kialea, with the result that while the prices of base metals continue to slump, diamond prices have likely bottomed, according to Petra Diamonds Ltd. The price of aluminum fell 19 percent last year, while copper and tin fell 25 percent, zinc dropped 26 percent, and iron ore plunged 39 percent.