Sea glass is glass that has been weathered and tumbled in water. It can be found along the shores or in the river- or seabed of any body of water in the world. Sea glass which is found along an inland river or lake is sometimes called beach glass. It is usually less smooth than sea glass found on the beaches of the ocean.
Most sea glass starts as discarded glass bottles that beach lovers leave behind and boat lovers toss overboard. The most common colors of sea glass are the same ones as for the original glass. Kelly green and brown glass are by far the most common color used in beer, wine, and soda bottles. Clear glass, which clouds up as it erodes, can come from bottles, but it can also come from plates, jars, and even broken windows. This kind of sea glass sometimes turns light purple as it weathers.
Other colors are not used in glass as often, and are much rarer among sea glass. Some colors are so rare that they can be tracked exactly to which company made that kind of bottle and when. In some cases, that type of bottle has not been made in over a hundred years.
Reds, pinks, blacks, and especially orange sea glass are the rarest of all. Some of these originate from nautical tail lights, while others come from bottles that are over 2 hundred years old. A red piece of sea glass is only found once in every 5,000 pieces, while orange sea glass is only found about once in every 10,000 pieces.
A few pieces of sea glass may even keep their original design. This is most common when the original substance is ceramic rather than glass. In this case, the proper term is sea pottery.
Once in the water, minerals inside the glass will gradually leach out. Wave action eventually breaks the original glass item apart. Sun, salt, and the surrounding sand and pebbles all combine to smooth and round the rough edges and gradually polish the piece. The salt may also add a distinctive etched look. Surface encrustations of lime and soda may give the polished glass a frosted look.
Beach glass, which is not as weathered as sea glass, can be found in larger pieces which retain more of their edges and are less likely to be frosted. In some cases, beach glass even retains part of an original embossed design.
Sea glass can also be made artifically by tumbling piees of glass in a rock tumbler. It won’t have the etched look of natural sea glass, but an acceptable frosted look can be obtained by soaking them in vinegar or lemon juice after tumbling.
As plastics have replaced glass for most uses, natural sea glass has become much harder to find. Unfortunately, there is no shortage of plastics among sea trash, which are much more dangerous to ocean wildlife than tumbled glass fragments. It does not take long before glass exposed to wave action becomes just another sea floor pebble, and marine life is adapted to deal with pebbles. However, it is not adapted to deal with shredded plastic, and many birds and fish die as a result.