Josie Iselin, the author of Abrams' popular Heart Stones , turns to sea glass hearts for a companion volume that promises to be just as appealing. Beachcombers the world over treasure sea glass--the shards of broken glass that are tumbled by the waves into smooth, pebblelike forms. They know which colors are common (green and brown) and which are unusual (black, yellow, red, and, especially, orange) and they can often identify the age and origin of...