Natural La Jolla: Treasure in trash — the beauty of sea glass

Tiny pieces of tile, pottery and china that have been tumbling in the surf for years. Photo: Kelly Stewart

[gallery]By Kelly Stewart

With sunny warm temperatures and cool Pacific waters, people love to go to the beach. Here is where you’ll find swimmers, sunbathers and surfers, but there’s another kind of beach lover that you’ll see — the beachcomber. These people wander slowly along the wrack line, heads down, intensely scrutinizing what the tide has brought in. They bend occasionally to pick something up, assessing whether or not it’s a treasure worth keeping.

When I’m beachcombing, I spend a lot of time picking up plastic so it doesn’t make its way into the ocean where it might be mistaken for food by marine creatures, but I have another reason for combing the beaches so thoroughly — sea glass.

Tumbled by the waves and sand for a decade or more, sea glass is a diminishing resource since we no longer dump our glass garbage at sea or off the end of a pier. Colors vary by where you are in the world and by what type of glass was thrown away. Brown and green are the most commonly found colors, those pieces began life as beer bottles. White is also very common and comes from soda or juice bottles.

In La Jolla I find very tiny pebbles of glass, of all different pastel shades. In St. Croix, in the U.S. Virgin Islands, where I am now and where I do field work during the summer, I can snorkel for hours in the clear Caribbean water searching for the perfect gem. Bits of tile and pottery are my favorites because I like to imagine the history of the plate or pot before it went into the sea. Broken china and porcelain plates were often used as ballast in ships that crossed the Atlantic during the sugar plantation days of the 18th and 19th centuries.

Festivals and craft shows have sprung up around the sea glass resource and the hobby constantly draws more devotees. Although sea glass may be manufactured by tumbling broken glass in a rock tumbler or by washing it in an acid bath (this is the sea glass you find at craft stores), purists insist on collecting it from the beach because each piece is unique and looking for it is so much fun.

Kelly Stewart, Ph.D. is a postdoc with NOAA’s Southwest Fisheries Science Center. Contact her at