Miranda Hollingshead, 27, was visiting the Crater of Diamonds State Park in Arkansas in a family outing.
They'd been at the park for about an hour, when she decided to take a break at the base of a hill. She fired up the YouTube video and started watching.
The park allows its visitors to search for diamonds in a designated 37.5-acre area.
For a second, she glanced over to check on her child before returning to the video. That's when she saw it: a yellow diamond, sticking out among the other rocks.
"I shook my hand across it to make sure what it was, picked it up, and yelled across the field to my mom, 'I think I got one!'" she told park officials.
She was right.
The 3.72 carat gem is the largest registered at the park since March 2017, when a teenager found a 7.44 carat brown diamond, according to the park. It is, however, the largest yellow diamond found since October 2013, when a visitor from Oklahoma City found one weighing in at 3.85 carats.
Just last month, a Nebraska teacher found a diamond in the same park, at 2.12 carats.
Hollingshead's diamond is about the size of a pencil eraser, according to a statement from Park Interpreter Waymon Cox.
He said the rain may have played a role in Hollingshead finding her diamond.
"Much of the ground where Ms. Hollingshead found her diamond is made of unweathered volcanic rock. When it rains, flowing runoff often leaves loose gravel, and sometimes diamonds, on the surface in these areas," he said.
So, schedule a trip to the park after a thunderstorm? Got it.