I just realized, I haven't really discussed the basic question -- What is sea glass? Many of my customers and potential customers ask this question. Some think that it actually is made by the sea, kind of how the earth produces diamonds, rubies, etc. In fact, sea glass is derived from a man-made material, i.e. glass. The glass can be from art glass, dinnerware, bottles, lights, etc. Often the broken pieces have been discarded and wind up in a dump or in the ocean. Some sea glass pieces are from the 1700's! If you have ever seen ancient Roman glass, you know that glass has been created by mankind for centuries.
Once the glass is in the water, it is tumbled by the waves and its actual physical characteristics are altered. Whereas once it was glassy, transparent, and sharp edged, it becomes gem quality sea glass after many years of tumbling in the sea. Then the glass is smooth edged, often opaque, and has a frosty appearance. Beach glass collectors often toss back pieces which are not completely finished, for another collector to find one day.
It can be a challenge to figure out the origins of a sea glass piece. Richard LaMotte, author of Pure Sea Glass, describes many bottles, insulators, etc. that can be considered. It is a good reference work for those of you who want to become more knowledgeable.
If you review my other posts about Fake vs. Real Sea Glass, you also will learn that often fake sea glass is sold by the piece or pound or in jewelry. It is important to recognize that machine tumbling broken bottles is not sea glass. SEA GLASS IS ACTUALLY A MAN-MADE MATERIAL THAT IS REFINED BY THE SEA.
Unlike other gems, which are nature's own and then refined by humans.
It is true ecological jewelry, since it is taking waste and creating something beautiful with it! Even if you just collect the sea glass you find, you are not harming the environment in any way.
One more note -- Recently in Bermuda, I saw baskets of cobalt blue, white, and aqua "sea glass" being sold by the piece in gift shops. They were sharp, and some clearly came from the same bottle source. Also, they were sold by the size, not the color. With cobalt blue being so rare, it is a red flag right there that the pieces were manufactured, made to resemble sea glass. Please be careful if you choose to buy sea glass or sea glass jewelry. Know what you are paying for. I hope this helps.