The cheapest synthetic gems
Glass is a low price synthetic gems and is used to imitate nature gems & jade-like chalcedony, quartz, beryl(emerald and aquamarine), emerald, nephrite, topaz, and so on.
Then the insoluble calcium compounds is formed in the glass which decides the glass is translucent or opaque.
Glass is an amorphous solid that has been around in various forms for thousands of years. Its heat transfer is slow. It’s fragile, light, and scratch easily while a low price is its biggest advantage.