The electromagnetic spectrum encompasses the entire continuous range of all electromagnetic radiation, extending from high-energy cosmic and gamma rays with sub-picometer wavelengths to kilometer-long radio waves. Visible light occupies only a minuscule fraction—roughly 380 to 750 nanometers.
Modern analytical spectroscopy leverages specific regions of this spectrum to interrogate matter: Ultraviolet (200–380 nm) reveals electronic bandgaps; Visible (380–750 nm) captures chromatic absorption and photoluminescence; and Near-Infrared (750–2500 nm) investigates molecular overtone and combination vibrational bands.
By extending observation beyond what human eyes can perceive, scientific instruments access previously hidden dimensions of materials, enabling unambiguous discrimination of natural vs laboratory-grown stones and identifying synthetic coatings or fracture-filling resins.