Sarine Technologies Ltd., a diamond manufacturing equipment maker and bellweather for the industry, reported a 42% plunge in its second-quarter revenue as demand for polished in its key markets weakened and rough prices rose. Sales plummeted to $14.4 million during the three-month period that ended June 30, dragging the company’s net profit for the quarter to $2.7 million, a 69% drop from a year ago. Recurring sales, which account for about half of Sarine’s operating revenue, slid 20%. Revenue fell on weak demand for polished in most markets. Excess polished inventory combined with relatively high rough prices and lower polished prices dampened sentiment among diamond manufacturers. Industry observers look at the company’s results as an indicator of the overall health of the diamond market because its revenue is generated from the sale of new equipment and recurring usage fees.