However, a yearlong stay in the United States brought the 45-year-old Beijinger into contact with the world of stone painting, and she's never looked back.

In June 2013, Tang began living on her own in Connecticut, while her son studied at a boarding school in the state. To alleviate homesickness and loneliness, the history graduate and sports fan often took walks along a nearby river, where the paths were littered with beautiful, flat stones no bigger than her palm. She decided to decorate the stones with watercolors and oil paint as a way of passing the time.

Tang says her work either expresses the affection between parents and children, or her own longing for home and family. A few paintings, featuring flora and fauna, reflect the beauty of the natural world.

Tang's work attracted the attention of art professionals, which led to her being interviewed by a Chinese art magazine, which also published photos of her work.

At a friend's suggestion, she opened an online shop for her artwork. "Many parents like the animals I paint and want to buy them for their children," she said. Each 12-stone set of paintings depicting animals sells for about 1,000 yuan ($163).

There's one painting she won't sell, though: It shows a woman and a boy sitting side by side on the grass, watching the stars in the night sky. The inspiration came from Tang's memories of stargazing with her son. "We used to watch the stars together years ago when my son was very young, just as the painting shows," she said.

Now Tang is back in China and she desperately misses her son. "Parents should treasure every moment they can spend with their children," she said.