Dichroic glass, also called fusion glass, is glass treated with various metal oxides to make it appear to have many colors. Developed for use in the American space program, dichroic glass is now popular as a jewelry and art material. The name comes from a Greek word meaning “two colors.”
In the 20th century, the National Aeronautics and Space Administration (NASA) began experimenting with treated glass to make astronaut face-plates that would block harmful spectrums of light. The developed process created dichroic glass, which uses fine layers of metal oxides to fracture and separate lightwaves. The resulting substance is used on a variety of objects, such as satellite mirrors and scientific instruments. It is also found on commercial products such as mirrors and camcorder lenses.
To make dichroic glass, the glass must be sprayed with micro-layers of metals, usually including titanium, chromium, gold, zirconium, and aluminum. This is conducted in a vacuum chamber, which evaporates the metals and fuses them to the glass in extremely thin layers. The fusion process creates a crystalline structure on the glass, which causes light to fracture. Each piece of dichroic glass has at least three colors: the color that reflects from the glass, the color of the glass, and a second refracted color that can be seen at a 45 degree angle. The process requires special equipment, and can be quite expensive to produce.
Treating the glass in this manner is somewhat similar to the Italian process of making Murano glass. This process has been used in Italian styles of jewelry and ornamentation for hundreds of years, and also employs metal oxides to create color and alter translucency. With Murano glass, the metal elements are added to a super-heated silicate just before it hardens, interweaving the colors and refractions with the actual glass. Because of the mixing process, Murano glass often appears to be multiple shades of one color, rather than the iridescent or rainbow colors apparent in dichroic glass.
In jewelry, dichroic glass is often formed into beads. In order to do this, the dichroic layer of glass is fired in a kiln with other layers of glass that encase it. Depending on the effect desired, the glass can be fired many times at a variety of settings, adding more layers if necessary. Dichroic glass beads are colorful and can be made in a variety of different shades, depending on the type of metals used in the vacuum process.
You can find dichroic jewelry in any color of the rainbow, available at jewelry stores and online shops. Because the process is costly, a single pendant or large bead may seem comparatively expensive for glass. Individual beads are available for approximately $20 US Dollars (USD) and up, while bracelets and necklaces comprised of the beads begin at around $70 USD. Earrings, which are usually rectangular or triangular in shape, can be found for about $18 USD.
