Thank you to the University of  Glasgow engineers who made this nano Christmas card (from  the University of Glasgow website),

Professor David Cumming and Dr Qin Chen from the University of Glasgow's School of Engineering etched the Christmas tree image onto a minute piece of glass

From the Dec. 23, 2010 news item on Nanowerk,

The colours were produced by plasmon resonance in a patterned aluminium film made in the University of Glasgow’s James Watt Nanofabrication Centre.

To get a sense of the scale, here’s a black and white version of the tree shown beside a human hair (from the University of Glasgow website),

Invisible to the naked eye, the card is so small that 8276 of them could fit on an area the size of a first class stamp.

The engineers had a reason for this project (from the news item),

Professor Cumming said: “Our nanotechnology is among the best in the world but sometimes explaining to the public what the technology is capable of can be a bit tricky.

“We decided that producing this Christmas card was a simple way to show just how accurate our technology is. The process to manufacture the card only took 30 minutes. It was very straightforward to produce as the process is highly repeatable – the design of the card took far longer than the production of the card itself.

“The card is 200 micro-metres wide by 290 micro-metres tall. To put that into some sort of perspective, a micro-metre is a millionth of a metre; the width of a human hair is about 100 micro-metres. You could fit over half a million of them onto a standard A5 Christmas card – but signing them would prove to be a bit of a challenge.”

Hope you all have a lovely Christmas/Hanukkah/Kwanzaa/??? holiday.

ETA Dec.24.10: I think this is more of a micro Christmas card as all of of the measures are in micro-metres rather than nanometres but it does seem the closest I’m going to get to a nano-sized Christmas card this year.