This icon, while well known among the Orthodox, is less well known to non-Orthodox Christians.
It is called "The Holy Napkin" or the icon "Not Made with Hands" as it is supposed to have been created as Christ wiped his face with a napkin.
I have inserted below the story of how this icon came to be and what it was intended to accomplish. I hope you find it interesting.
(Christ Not Made By Hands or Holy Napkin)
According to Bishop Nikolai Velimirovich in The Prologue from Ohrid:
"In the time that our Lord was preaching the Gospel and healing every disease and every infirmity among the people, there was in the city of Edessa, on the banks of the Euphrates, a certain Prince Avgar, who was riddled with leprosy. He heard of Christ, the Healer of every pain and sickness, and sent a portrait-painter, Ananias, to Palestine with a letter to Christ, in which he begged the Lord to come to Edessa and heal him of his leprosy. In the event of the Lord's not being able to come, the prince commanded Ananias to paint His likeness and bring it, believing that the portrait would heal him.
The Lord replied that he could not come, as the time of His Passion was at hand, and He took a napkin and wiped His face, leaving a perfect reproduction of His most pure face on the napkin. The Lord gave this napkin to Ananias, with a message to say that the prince would be healed by it, but not entirely, and He would therefore send him later an envoy who would rid him of the remainder of the disease.
Receiving the napkin, Avgar kissed it and the leprosy fell from his body, with just a little remaining on his face. Later, the Apostle Thaddaeus [one of the 12 apostles], preaching the Gospel, came to Avgar, healed him secretly and baptised him.
Then the prince smashed the idols that stood at the city's gateway and placed the napkin with the face of Christ above the entrance, stuck onto wood, surrounded with a gold frame and ornamented with pearls. The prince also wrote above the icon on the gateway: 'O Christ our God, no-one who hopes in Thee will be put to shame'.
Peace be with you.