"NEW YORK (Reuters) - commodity prices fluctuated wildly on Wall Street today as a sudden spike in diamond prices prompted a sharp decline in all other forms of demand. The Dow Jones closed down 4%, and Brent Crude closed down 10%. Experts cited 'irrational exuberance' akin to that of the dotcom boom and argued that the formerly stagnant diamond commodities market had previously remained small for sound economic reasons; they also urged the Federal Reserve to intervene..."