DIAMOND giant De Beers said on Monday that it aims to cut its working stockpile of diamonds to between $1,5-billion to $2,0-billion from $4,6-billion at the end of last year. “The working stock level in London will be cut over some time . . . We will be working hand-in-hand with incremental demand so we don’t affect the market,” De Beers spokesman Tracey Peterson said. Last week, De Beers announced a shift in its marketing policy under which the firm will focus on increasing global demand for diamonds rather than simply relying on building up its stockpile of gems in London in order to control market supply.