Approximate wavelength (in vacuum) and frequency ranges for the various colors

Color                  Wavelength (nm)             Frequency (THz)

Red                     780 – 622                            384 – 482                                     
Orange               622 – 597                            482 – 503                    
Yellow                597 – 577                            503 – 520                         
Green                 577 – 492                            520 – 610                            
Blue                    492 – 455                            610 – 659                        
Violet                  455 – 390                            659 – 769


1 terahertz (THz) = 10³ GHz = 10⁶ MHz = 10¹² Hz, 
1 nm = 1e-9 um = 1e-6 mm = 1e-3 m.