Roman Glass Bracelet - Height 1cm - Very Good Condition - Some places they used it into jewllery becouse of the natural colours - The most common natural colors of the glass are blue and green. This is how the glass was first created, and is due to the natural minerals in the sand used during process. After many years in the ground, the glass often develops a thin iridescent coating known as patina. This patina reflects the light in a beautiful opal-like multicolor glow.