Saurashtra Cement Ltd. said on Tuesday its board had approved an issue of convertible debentures worth 931.25 million rupees to Cayman Islands-based ADM Maculus Fund II LP.   The cement manufacturer said 260.75 million rupees worth would be converted mandatorily within 18 months into 7.45 million shares at a conversion price of 35 rupees per share. The rest would be convertible at the option of the holder within 18 months into 5.364 million shares at a price of 125 rupees each.   Shares in Saurashtra closed 4.7 percent higher on Tuesday at 45 rupees.  
 The board also approved an issue of 2.47 million equity warrants to British Virgin Islands-based TORO Managers Ltd., and 0.5 million warrants to Mumbai-based Brescon Corporate Advisors Ltd., exercisable in tranches within 18 months and each giving them the right to subscribe to one share at 35 rupees each.