Gems and gem materials, by Edward Henry Kraus and Chester Baker Slawson. Kraus, Edward Henry, 1875-1973. Slawson, Chester Baker, 1898- joint author. Precious stones. QE392 .K7 1947 553.8 19 KRG "Selected bibliography": p. 317-319. New York, McGraw-Hill Book Co., 1947. 1947. 1947 Text ix, 332 p. : eng