Other of Mr Lindon’s tiny creations include unique animals crafted within the eye of a needle, from a blue whale to a delicate peacock butterfly.
“I probably am completely bonkers,” he jokes.
The stamp where Yellow Smiley Face lives is mounted on a glass tower and housed inside a sealed glass box.
Mr Lindon said he was grateful to Dr Sarah Elliott and Jack Rose from Bournemouth University for measuring the new world record.
He said he created a micro sculpture of a graduation certificate being grasped by the hand of a newly qualified student, which is “less than a millimetre wide and set on a solid gold plinth”.
The artist added the artwork would be gifted to the university “to inspire future generations”.