RAPAPORT... The price cuts that took effect in the rough-diamond market last month surprised some, but made perfect sense given the trends in polished trading and the recent earnings reports from De Beers and Alrosa.The September issue of the Rapaport Research Report, which was published Monday, outlines the main considerations that led De Beers and Alrosa to reduce rough prices in August. As major mining companies, they walk a fine line between supporting the market and keeping shareholders happy. And this balancing act means that slight changes in their supply policies could spell the difference between a shortage or an oversupply of polished during the holiday season. The Rapaport Research Report also offers exclusive data for 0.30-carat, 0.50-carat, 1-carat and 3-carat polished diamonds, including average prices, discounts, inventory by country, and search volume. In addition, it presents the volume of goods moving onto and off of RapNet, and the average time it takes them to do so. To subscribe and download your copy of the report, click here and log in with your username and password.Image: Cover of the September Rapaport Research Report. (Shutterstock and Alrosa)