How is Sea Glass formed?

Holding a piece of green sea glass at the beach with the sun shining through it.
How is Sea Glass formed?

When you’re walking along the beach, you may have spotted some brightly colored, rock-like objects, or you may already be one of those who are enchanted by their gem-like appearance.

Frosted and rounded, sea glass have been used in jewelry and the making of other decorative projects, like mosaics and jars for decades. They have many names, from ‘sea gems’ and ‘beach jewels’, to ‘mermaid’s tears’ and ‘sea pearls’.

But have you wondered about how sea glass came to have its appearance, and where they came from? Here is a primer on how sea glass is formed.

What is Sea Glass Made of?

Sea glass comes from shards of broken glass which originated as bottles, jars, glassware, table ware or even as the result of shipwrecks. The most common source of glass is from companies that sell beer, juice and soft drinks.

Not as common, is glass that comes from clear plates and glasses, windshields, windows, whiskey, medicine, spirits and early bleach bottles. Other sources are soda bottles from the 1960s, ink bottles, and fruit jars from the late 19th to early 20th centuries.

Before, when environmentalism wasn’t yet a priority, people often tossed their refuse wholesale into large bodies of water. That still happens today, when vessels of all kinds dump their garbage, including assorted glassware, into the sea.

Discarded into the sea, larger glass pieces shatter, break, and are then tumbled, tossed around by the waves, weathered by salt water and friction with other materials in the sea until they obtain a glassy, etched and unique appearance.

Sea glass can be clear, white, green, blue, jade, aqua, amber and brown, but never shiny. The slick and glossy appearance of glass has slowly transformed over the years into its special, frosted look, especially when salt water leaches into the glass and when exposed to sun light. Sea glass also has no sharp edges, unless it has been broken.

A piece of yellow sea glass laying on top of sea shells.

By Pere López - Own work, CC BY-SA 3.0,

Sea Glass vs. Beach Glass

Tides, other than serving to tumble and toss these glass fragments around, eventually help to wash sea glass up on to beaches. The difference between beach glass and sea glass lies in where they are found, which in turn affects how they are formed.

Beach glass is found on either freshwater or seawater beaches, whereas sea glass is found only on saltwater beaches. These two terms were created to distinguish between the slight difference in appearance between the two.

While the differences are sometimes so slight that it’s hard to discern, saltwater beaches are a lot more common, and often produce the tumbling action that’s required to form sea glass. Beach glass can sometimes be found on a lake too, such as the Great Lakes in the United States.

Beach glass usually appears less weathered, and may even still have some shiny spots due to the relatively tamer tumbling action, as compared to seas and oceans. Therefore, while all sea glass is beach glass, not all beach glass is sea glass.

Sea glass is commonly found along the beaches of the northeast United States, California, northwest England, Mexico, Hawaii, Puerto Rico, Australia and Italy.

Length of Time to Make Sea Glass

Depending on the amount of wave action, sea glass can take as little as 5 years to form, but on average, it takes about 20 to 30 years. They can also sometimes take as long as 50 years. For sea glass to acquire its appearance, the most important ingredient and factor is time - there’s just no substitute for it.

Chemical and physical weathering processes are slow, needing repetition and force for them to take effect and transform pieces of glass, into the beautiful sea glass you find on a beach. So count yourself lucky to be holding a piece of sea glass so lovingly and patiently transformed by Mother Nature herself!

A collection of beach treasure on a tabletop, including sea glass and sea shells.

By Hughman (Own work) [CC BY-SA 3.0 (], via Wikimedia Commons

Why is Sea Glass Getting Harder to Find?

Sea glass is getting harder to find for a few reasons. One of them is a positive one - there is just less dumping in the oceans today. Less trash, less glass, which leads to less sea glass. Additionally, many glass items have been replaced by plastic. So even with the trash that is getting dumped into bodies of water, plastic just doesn’t break down the way that glass does.

On top of that, more people are now searching for sea glass along the shores and are collecting it. So chances are, before you get the opportunity to stumble upon a piece, an eagle-eyed collector may already have swooped down on it!

Sea glass has been used in art for many years, and for a good reason! It is beautiful, and inspires wonder in those who love tracing their history, and imagining the path it took for these shards of household glass to wash up on a beach as a bright piece of sea glass.

Once you know about the journey your sea glass has been on, you’ll be able to appreciate it all the more when you are lucky enough to spot one on a beach!



I have been gathering sea glass for many years. I can never resist a stroll along the beach and the opportunity to add some more beach treasure to my collection!


  1. is there Or has there Ever been a World Championship for the BesT formed Shard of Ocean Sea Glass along theSame line’s as being theMosT BeauTiFuL Color or theRariesT Color ? T – You

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