HECKER, Ill. — The first fingernail tattoo started off as a joke.

The client, a man who had lost part of two fingers in a construction accident, wandered into Eternal Ink Tattoo Studio and asked for a fingernail design at the tips of his fingers. It was his way of making light of a bad situation.

The idea amused everyone in the studio. But once Eric Catalano, the owner, had finished the tattoo and put away his needles, “the mood changed in here,” he recalled recently. “Everything turned from funny to wow.”

A photo of the inked fingers went viral, and Mr. Catalano, 39, was thrust into the emerging world of paramedical tattooing. The fingernails looked so realistic that even “Ripley’s Believe It or Not!” tracked him down to feature his work.

“There was a lot of pressure after that,” Mr. Catalano said. “I was so nervous. But it turns out the next one came out amazing. Just like the first one.”