What Is Sea Glass and Where to Find It, According to Beachcombers

There is a soft crash and then a faint tinkling as the waves nudge small trinkets—shells, rocks, and, sometimes, glistening fragments of colored glass—ashore. Shining in the sand like so many emeralds, sapphires, opals, and bits of amethyst and aquamarine, the burnished shards known as sea glass, look as if they might have been emptied from a treasure chest anchored to the ocean floor.

How Sea Glass Is Made

Unlike true jewels, which are created in nature and refined by humans, sea glass is made by man and finessed by the natural world. Until the 1960s, it was common for sanitation departments in coastal towns, not to mention the average beachgoer, to dispose of waste, including glass and broken china, in the water. These objects would break and be worn smooth by periods of submersion and continuous tumbling over rocks and sand, eventually turning up on beaches. (In some regions, the shards are called beach glass.) Because of the way glass breaks, rough triangular shapes are the most common.

Richard LaMotte, author of Pure Sea Glass ($28.49, amazon.com), says it takes at least 20 years for a jagged shard to be transformed into a sufficiently polished specimen. Of course, a lot of glass is much older. Green and brown are among the most prevalent colors, owing to the vast number of bottles manufactured in these hues since the 19th century. Clear glass, used for bottles starting in the early 1900s, is equally widespread. Far more difficult to find are blue, pink, and purple pieces. Red, yellow, black, and gray are rarer still, and many people consider orange to be the sea glass collector's holy grail. Regardless of color, pieces found near the ocean have a frosted patina, because of heavy corrosion, whereas those shards that emerge from lakes and rivers, which are less abrasive, are usually more translucent.

When to Look for Sea Glass

The best time to comb for sea glass is after a strong storm, which churns up the water and sends waves to batter the shore. If you're heading to the ocean, set out at low tide, when the greatest expanse of beach is exposed. You'll have even better luck if your search coincides with a full or new moon, both of which exercise a powerful gravitational pull on the sea, causing it to recede farther and expose more.

Once you get your cache home, there are countless ways to display it: by heaping pastel shapes in clear vessels on a mantel, embedding bits in a tiled tabletop, or turning the pieces into jewelry. The glass may not be as costly as real gems—a half pound of shards in familiar colors can sell for less than $10 through online auctions—but its quiet beauty, and the satisfaction that comes with unearthing it yourself, makes it no less precious.

Where to Find Sea Glass, from Coast to Coast

Sea glass is less plentiful today than it was in the past for a few reasons, including beach erosion and the wide use of plastic and aluminum packaging. And, fortunately, more people are recycling glass. But you can still find shores that are littered with shards. Here, Richard LaMotte reveals his top five spots. First up is Glass Beach in Fort Bragg, California, which is the site of a public dump that was active from 1949 to 1967. There are treasures to be found here, though. This beach in the northern part of California has almost as much sea glass as sand. "People bring back buckets," LaMotte says. Then there's Glass Beach in Port Allen, Hawaii. Stretches of this black-sand beach, which is located on the southern side of Kauai, are thickly spread with shards; they're also embedded in the surrounding cliffs. A communal dumping ground until the early 20th century, the area can be hit or miss, he says. "Shifting sands will uncover massive beds of glass one day and cover them up the next."

Next time you find yourself in Bermuda, be sure to make a stop at Buildings Bay Saint in George's. The beach in this small cove next to Alexandra Battery, an 1860s-era fort, is strewn with glass. "You can kneel down and pick up 50 good-sized pieces," says LaMotte, who found a mix of shards from the 19th and 20th centuries, including some rare black specimens. Another spot worth visiting? Playa Media Luna in Isla Mujeres, Mexico. The northern end of this beach, located on an island eight miles offshore of Cancún, is dotted with glass. LaMotte has found mostly twentieth-century fragments here. Last but not least is River Mouth in Rincón, Puerto Rico. Glass shards ring a 50-yard-long tide pool in this secluded spot, a 15-minute walk from Antonio's Beach, on the north side of town.