Jewelry grade glass is cured/frosted has no chips and is generally even in thickness. It is smooth on all sides and surfaces. Shape and size determine its monetary value and usability within the design trade.
Pairs of sea glass that are approximately the same shape are extremely valuable in the jewelry business because they can be made into earrings and matched with complementary stones and gems. They are unique as no two pieces of glass are exactly the same and glass cannot be duplicated.
Generally from shipwrecks and shore fires. It has been exposed to high temperatures. Bonfire glass is identifiable by its bubbly surface or having fragments of shells, stones and sand lodged inside. It is considered very rare.