Colored stone inventories are wideningThe colored stone market continues to see prices rise on increasing demand in world markets. Natural fine quality sapphire has reached a price plateau that eliminates the vast majority of customers from being able to afford it. In spite of that trend, however, many gem varieties remain affordable, even in the finest qualities.Dealers report that demand is strong for 5 ct.-plus tourmaline, especially the intensely bright blue, blue-green, and green colors. Prices for these stones have increased in response to demand. Exceptionally well-cut goods in the 3 ct. to 8 ct. range are bringing upward of $1,200 per carat for extra-fine mint green material. Beryl, especially fine aquamarine, is also in demand this summer. Dealers report that prices for fine quality material have stabilized after experiencing a general upward trend since 2009. Demand for mo