Colored glass flecks or shards were used to decorate glass vessels made in Italy, c. 30 - 70 A.D.  The technique is similar to and replaced fine-grain decoration but the glass is rolled through the colored glass flecks at an earlier stage.  The flecks melt flush with the surface and also expands in size and distort in shape as the glass is blown (most noticeable in the neck where the flecks elongate).