Blue + White = Light Blue... Blue + Black = Dark Blue.
Green + White = Light Green... Green + White = Dark Green.
Purple + White = Lavender = Light Purple... Purple + Black = Dark Purple.
Red + White = Pink, only Pink, never Light Red, only Pink, which I find hilarious and confounding.
Yellow + Black = some color that you might mistake as Green and you might mistake as Brown but no one would ever call Dark Yellow. I love that color.