On an unseasonably warm October afternoon in the New York Botanical Garden, a girl with iridescent butterfly wings painted across the bridge of her nose watches Sergey Jivetin at work. He sits at a microscope, his attention focused on a seed beneath a jeweler’s blade. Patiently, he chats with her while etching on his Lilliputian canvas, until he hands the seven-year-old an image of a butterfly no larger than the tip of her thumb. Since 2016, Jivetin has carved more than 500 intricate images onto seeds, mostly as gifts for…