Miranda's right - no surprise there! It's used nowadays for a rather harsh green pigment, very chemical-looking; an art shop would show you. But in Latin it also had the meaning of 'fresh and young', which I imagine is what the saint's name would have referred to, rather than the paint... The -i- spelling is closer to the Latin. But the -e- spelling looks as if it might have been influenced by 'ver-', meaning 'true', like Veronica.