Gold no longer has to be golden: British team finds way to change the precious metal's hue

  • Process could be used to make banknotes more difficult to forge
  • It can be applied to any metal and change it to any colour

By Daily Mail Reporter

PUBLISHED: 10:01 EST, 25 October 2012 | UPDATED: 10:01 EST, 25 October 2012


British scientists have managed to upstage King Midas by changing the colour of gold.

While the mythical king turned everything he touched to gold, the researchers transformed the precious metal by altering the way it absorbs or reflects light.

So gold no longer has to be golden - it can be red or green, or a multitude of other hues.

All that glisters: Gold has here been treated to spell out the words 'nano meta' - pictured here through an optical microscope

All that glisters: Gold has here been treated to spell out the words 'nano meta' - pictured here through an optical microscope

The technique involves embossing tiny raised or indented patterns onto the metal's surface.

It can also be applied to other metals, such as silver and aluminium, and opens the way to colouring metal without coatings or chemically treatments.

Applications may include anything from manufacturing jewellery to making banknotes and documents harder to forge, say the scientists.

 

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Professor Nikolay Zheludev, who leads the University of Southampton team, said: 'This is the first time the visible colour of metal has been changed in this way.

'The colours of the objects we see all around us are determined by the way light interacts with those objects. For instance, an object that reflects red light but absorbs other wavelengths will appear red to the human eye.

'This is the fundamental principle we have exploited in this project. By embossing metals with patterns only around 100 nanometres across, we've found that we can control which wavelengths of light the metal absorbs and which it reflects.'

Hi-tech: A researcher uses one of the nano-fabrication machines used in the process

Hi-tech: A researcher uses one of the nano-fabrication machines used in the process

The shape and height, or depth, of the patterns determines exactly how light behaves when it strikes the metal and what colour is created.

Different parts of the same surface can be made to reflect light differently. A silver ring, for example, could be decorated with a rainbow of multiple colours.

Metal elements with optical properties that would be almost impossible to forge can also be incorporated into documents as security features.

Prof Zheludev added: 'We've filed a patent application to cover our work, and we're currently talking to a number of organisations about taking our breakthrough towards commercialisation.'

Details of the research have been published in the journals Optics Express and the Journal of Optics.

The scientists received funding from the Engineering and Physical Sciences Research Council as part of a £5million project looking at photonic nanostructures.

 

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I am not sure how they can limit this process to producing only a single colour as the angle of light being reflected is not uniform at all times and the angle of incidence affect the order of refraction if I can remember my A level physics well). nLambda=d sine Theta - Jetty , London, United Kingdom, 26/10/2012 09:39......This has nothing to do with refraction. It is similar to stained glass where it is the size of small metal particles that produce the colour. Here I think that they are making nanometer size holes in surface, changing the size of the holes makes the different colours. The process is described in part by Wiki on surface plasmon resonance.

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Is it posible to make it look like tungsten?

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I thought the whole point of owning gold was because its ..... GOLD colour .... reminds me of the sketch in Blackadder where Percy descovers Green - Billy Bob Precisely. Or when Queenie said of the boomerang, "What is the point of that? If I throw a stick away it is because I don't want it to return."

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RossD89 , Lancashire,- Who reads DM articles, who has trhe time, they are invariably full of inaccuracies. spelling and grammatical howlers. The headlines suffice for most foks, or the totty in bikinis that is a good alternative. lol - Well obviously you do RossD89, and you also have a couple of spelling howlers included just for good measure (trhe instead of the, and foks instead of folks). You are aware that the comment panel has a spell check no?

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This is a bit pointless. If you textured gold jewelery to have a refractive surface it would wear off fairly quickly so you would need to laquer it perhaps, which takes away from the fact it is 'everlasting' gold. (I worked in the Jewelery industry for 5 years). Also, I am not sure that a person could tell the difference between this technique on a banknote and other ways of tinting metal different colours. Metals can be plated thinly to have hues and tints more easily than this process does so forging something very close to how this looks would not be that difficult at all. The little colourfull rainbow reflector on a credit card or already on a banknote uses this refraction principle to produce colours. I am not sure how they can limit this process to producing only a single colour as the angle of light being reflected is not uniform at all times and the angle of incidence affect the order of refraction if I can remember my A level physics well). nLambda=d sine Theta

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I thought the whole point of owning gold was because its ..... GOLD colour .... reminds me of the sketch in Blackadder where Percy descovers Green

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RossD89 , Lancashire,- Who reads DM articles, who has trhe time, they are invariably full of inaccuracies. spelling and grammatical howlers. The headlines suffice for most foks, or the totty in bikinis that is a good alternative. lol

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This has to be about security. We all know to tea leaf the 'gold' stuff. Would you be as quick to tea leaf metal that was sky blue pink?

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A nugget of purest green

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The advance here is in finding a method of copying the colour mechanism found in butterflies and many other creatures. The pigment-free methods of generating colours arecapable of producing some of the most vibrant colours.

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