Scientists in Southampton are now able to change the color of the world’s most iconic precious metal, gold. They did this by embossing tiny raised or indented patterns onto the metal’s surface. This changes the way it absorbs and reflects light. With this discovery, gold can be made red or green or many other colors without any coating or chemical treatment. This technique works well with other metals like silver and aluminum as well.
The basic principle behind the colors of objects we see all around us is determined by how the light interacts with those objects. For example, any object which reflects yellow light but absorbs other wavelengths will appear yellow to us.
Researchers found that the shape, height and depth of the embossed patterns determines how light behaves when it hits the metal and hence what color is created. They observed that by embossing metals with patterns only around 100 nanometers across (400 times thinner than the human hair), they can control which wavelengths of light the metal absorbs and which it reflects.
This technique can be used in a wide range of industries. It can be used in making beautiful jewelry. It can also be used to make banknotes and documents as a security feature because the metals are difficult to forge.