In the land of Eden, sea glass is a coveted material. Because the one sea in Eden dissolves any and all garbage thrown into it, the only sea glass is to be found in Eden comes from the belongings of Earthling refugees—and how many of them just happened to be carrying sea glass when their reality was destroyed in The Calamity?
Among the nations of Eden, none covets sea glass more than The Ninth Empire of Oz. In fact, green sea glass is Oz’s most precious commodity next to their prized emeralds, and the two are often used together in building the great monuments of that land.
Sea glass is a derivative of manufactured glass waste. Imagines shards of a broken bottle or broken tableware, swallowed by the ocean tides then weathered by time and salt water until smooth and frosted instead of sharp, slick, and translucent.
The most common colors of sea glass are green and brown—not coincidentally the colors of the beverage bottles most commonly abandoned on beaches by careless (and drunk) human beings.
Origin & Source
According to Wikipedia, which is never wrong, “sea glass takes 20 to 40 years, and sometimes as much as 100 years, to acquire its characteristic texture and shape.”
During normal iterations of reality, such as Earth-668 and Earth-669, sea glass is collected by beachgoers visiting the oceans of the world—alongside sea shells and the like.