From minimalist yellow smiley faces to heart-shaped embroidery, nail pros are turning to thumbs to show off their most intricate creations. "With everyone posting close-ups of their hands on Instagram, thumbnail art has recently taken off," says Olive & June founder Sarah Gibson Tuttle. And nail pro Jessica Washick echos that the thumbnail accent is a subtle way to upgrade any simple manicure. "You can be as expressive as you want on your thumbs," she explains. "And then, you still have the classic look of a polished manicure on every other fingernail."