EGYPTIAN women traditionally receive a gold jewellery set, or "shabka", on their engagement. But as surging prices and a weakening currency have driven up demand for the precious metal, some are getting silver instead. The trend is a measure of an economic crisis in which inflation has been running at more than 30% and the central bank has allowed the currency to weaken 50% against the dollar, with more devaluation expected. "Silver is the new gold," said a salesman at a Cairo silver store who only gave his first name, Abanob. In the year to Jan. 30, the price of a gram…