Complex sentence: Gem-quality diamonds grown in a lab can be chemically, physically and optically identical to naturally occurring ones, although they can be distinguished by spectroscopy in infrared, ultraviolet, or X-ray wavelengths.
Split into simpler sentences: Gem-quality diamonds grown in a lab can be chemically, physically and optically identical to naturally occurring ones. Man-made diamonds can be distinguished by spectroscopy in the infrared, ultraviolet, or X-ray wavelengths.