Sea glass are naturally weathered pieces of glass, which often have the appearance of tumbled stones. Sea glass is physically and chemically weathered glass found on beaches along bodies of salt water. These weathering processes produce natural frosted glass. Sea glass is used for decoration, most commonly in jewellery. "Beach glass" comes from fresh water and is often less frosted in appearance than sea glass. Sea glass takes 20–40 years, and sometimes as much as 100–200 years, to acquire its characteristic texture and shape. It is also colloquially referred to as drift glass from the longshore drift process that forms the smooth edges. In practice, the two terms are used interchangeably.

Tumble finishing, also known as tumbling or rumbling, is a technique for smoothing and polishing a rough surface on relatively small parts. In the field of metalworking, a similar process called barreling, or barrel finishing, works upon the same principles.