Sea glass or beach glass is physically and chemically weathered glass found on beaches along bodies of fresh and salt water. These weathering processes produce natural frosted glass. Sea glass can be collected as a hobby and can be used to create jewelry.
Sea glass can be found all over the world, but the beaches of the northeast United States, Bermuda, California, northwest England, Mexico, Hawaii, Puerto Rico, Nova Scotia, Australia, Italy and southern Spain are famous for their bounty of sea glass, bottles, bottle lips and stoppers, art glass, marbles, and pottery shards. The best times to look are during spring tides especially perigean and proxigean tides, and during the first low tide after a storm.
Glass from inland waterways such as Chesapeake Bay and the Great Lakes is known as beach glass. It is similar to sea glass, but in the absence of wave rigor and oceanic saline, content is typically less weathered. Beach glass from inland regions often has prominently embossed designs or letters on it, which can make tracing its origin less challenging. The outer surface of beach glass shards may also be texturally varied, with one side frosty and the other shiny. This is most likely because they are pieces broken off from larger glass objects which are themselves still embedded in mud, silt or clay, slowly being exposed by wave action and erosion.
The color of sea glass is determined by its original source. Most sea glass comes from bottles, but it can also come from jars, plates, windows, windshields, ceramics or sea pottery.
The most common colors of sea glass are kelly green, brown, white (clear), blue, and purple (clear). These colors come from bottles used by companies that sell beer, juices, and soft drinks. The clear or white glass comes from clear plates and glasses, windshields, windows, and assorted other sources.
Less common colors include jade, amber (from bottles for whiskey, medicine, spirits, and early bleach bottles), golden amber or amberina (mostly used for spirit bottles), lime green (from soda bottles during the 1960s), forest green, and ice- or soft blue (from soda bottles, medicine bottles, ink bottles, and fruit jars from the late 19th and early 20th centuries, windows, and windshields). These colors are found about once for every 25 to 100 pieces of sea glass found.
Uncommon colors of sea glass include a type of green, which comes primarily from early to mid-1900s Coca-Cola, Dr Pepper, and RC Cola bottles as well as beer bottles. Soft green colors could come from bottles that were used for ink, fruit, and baking soda. These colors are found once in every 50 to 100 pieces.
Purple sea glass is very uncommon, as is citron, opaque white (from milk glass), cobalt and cornflower blue (from early Milk of Magnesia bottles, poison bottles, artwork, and Bromo-Seltzer and Vicks VapoRub containers), and aqua (from Ball Mason jars and 19th century glass bottles). These colors are found once for every 200 to 1,000 pieces found.
Extremely rare colors include gray, pink (often from Great Depression-era plates), teal (often from Mateus wine bottles), black (older, very dark olive green glass), yellow (often from 1930s Vaseline containers), turquoise (from tableware and art glass), red (often from old Schlitz bottles, car tail lights, dinnerware or from nautical lights, it is found once in about every 5,000 pieces), and orange (the least common type of sea glass, found once in about 10,000 pieces). These colors are found once for every 1,000 to 10,000 pieces collected. Some shards of black glass are quite old, originating from thick eighteenth-century gin, beer and wine bottles.
Like collecting shells, fossils, or stones, combing shorelines for sea glass is a hobby many beach-goers and beachcombers enjoy. Hobbyists often fill decorative jars with their collections and take great pleasure in tracing a shard's provenance while artisans craft beautiful pieces of jewelry, stained glass and other decorative pieces from sea glass. Some collectors even use their collections in creating beautiful works of art by putting them in cement or other adhesive to create a mosaic.
Authentic sea and beach glass is becoming rarer and harder to find for a variety of reasons: there are more people searching for it and littering has increasingly staggered the making of it naturally.
This scarcity has led to some artisans and crafters tumbling poorer pieces of sea glass shards to create what is called "twice-tossed" glass, while others create artificial sea glass, or "craft glass", from ordinary glass pieces using a rock tumbler. While such glass is chunkier than most true sea glass, lacks its romantic provenance, and differs in many technical ways, e.g. long-term exposure to water conditions creates an etched surface on the glass that cannot be duplicated artificially[verification needed] it does meet the demand of crafters at a cheaper price and in a wider range of colors.
- Barbara Weibel Best Beaches for Collecting Sea Glass www.uptake.com september 07, 2012
- Dean, C. From junk to collectible, shaped by time and tide. New York Times October 18, 2010
- North American Sea Glass Association
- NASGA: Genuine vs. Artificial
Further reading 
- National Geographic Magazine, "Environment" section: "The Shard Way," August, 2008
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