DE BEERS: NAMIBIA PACT BOLSTERS DIAMOND MARKET De Beers has signed a new diamond mining and marketing agreement with Namibia that company officials call a "ringing endorsement of the single-channel marketing" system that will bolster the confidence of the world diamond trade. The agreement keeps Namibia's very-high-quality diamond production firmly in De Beers' control but, in exchange, turns over half of the mining operations to the Namibian government. Both sides achieved their most important goals, says Abel Gower, executive director of Namdeb Diamond Corp., a new corporation jointly owned by De Beers and the Namibian government. Under the 25-year accord, De Beers received the right to continue marketing 100% of the country's diamonds. Namibia won joint management of its diamond resources and a commitment to build up local employment. Though De Beers ceded half the operation t