Seam mark
Glass Dictionary

A slight, narrow ridge on a glass object, which indicates that it has been made in a mold. The seams appear where gaps in the joins between parts of the mold have permitted molten glass to seep during formation. On well-made pieces, the seam marks are usually smoothed away by grinding or fire polishing.
Alternate Spellings:
seam marks
seam marked
seam-marked
mold-mark
mold-marked
mold marked
Term Variations:
Mold mark
Artwork Examples: