LPoD - dichroic glass

Today's learning point relates to the bracelet I received for mothers' day. It is made of beads of dichroic glass, which appear to change colour, depending on the angle at which you view them.

Dichroic coating was originally developed by NASA for the aerospace industry. The material is used in the visors of space helmets. I have also heard some reports that it is used in the Hubble telescope, but I have been unable to verify this. The glass contains microlayers of different metal oxides, applied using an electron bombarder inside a vacuum chamber. These reflect and refract light in different ways, resulting in the effect of different colours when it is tilted this way and that. In fact, no color is actually produced. The perceived colours are the result of light manipulation.

It is now very popular in costume jewellery design and manufacture, as much because of the price tag as the depth and range of colours. Because the reflection/refraction cannot be accurately predicted, no two pieces of dichroic glass are ever exactly alike.

Here's an example, picked at random from the many returns from a google search.