The gloss which occurs on the edge of flint sickle blades, and which is caused by the wear of the blade against the phytoliths in the grasses being reaped. A distinctive shine produced on flint tools which have been used to reap cereal grasses. The polish comes from the abrasive action of silica present in the stems of both wild and cultivated cereals, so the occurrence of reaping tools with sickle gloss need not by itself imply agriculture.