Dichroic Glass Shamrock Necklace holds a shamrock pendant approximately 1.25" in diameter. Sterling silver loop attached to an 18" sterling silver chain. The necklace is packaged in a gift box with an Irish blessing: "May your blessings outnumber - The shamrocks that grow - And may trouble avoid you - Wherever you go." The word "dichroic" comes from two Greek roots: "di" meaning "two" and "chroma" meaning "color". The complex processing techniques that create the multi-colored effect in the glass are called "thin film physics". This type of physics is responsible for the rainbow of colors in soap bubbles and the varied colors reflected through the wings of dragonflies. To create dichroic glass, metallic oxides are heated at very high temperatures and vaporized so that they create a covering on glass. Anywhere from 15-45 layers of these oxides can be used. While the metallic oxides have no color themselves, they create an optical filter on the glass that transmits or reflects various wavelengths of light differently, causing the multiple colors to appear in the glass and the apparent shifting of the colors as the glass is held at different angles. This assures that no two shamrock necklaces are the same.