(IDEX Online) - India's polished diamond sales are set to plunge by more than a quarter, say the ratings analysts CRISIL."If the trade disruption is protracted, next quarter's sales will be down by 25 to 30 per cent, shaving off about $2bn to 2.5bn," said its director, Rahul Guha, speaking before Friday's announcement of sanctions by the US government on the purchase of rough diamonds from Russia."That would mean flattish growth next fiscal. The decline would have been steeper but for the reasonably leaner period of the first half, when the industry generally reels in about 45 per cent of its annual sales. Any increase in the severity or tenure of the sanctions will have a deeper impact and remains a monitorable."CRISIL, an India-based subsidiary of S&P Global, said that before Russia's invasion of Ukraine it was predicting rough price rises of 10 to12 per cent on-year next fiscal.Now it is forecasting an additional rise of five to eight per cent amid the supply-side constraints.It is analyzing its portfolio of 53 diamantaires, representing a third of the industry's revenue, to see if their consignments are being delayed despite having paid Alrosa.