Answer with Explanation:
Every chemical element has an "emission spectrum" that is unique from the other. This spectrum consists of electromagnetic waves of varying wavelengths. The differences in wavelengths is brought about by electron transitions. These transitions produce different energy levels.
In order to know the elements that comprise a particular composition, the "spectroscopy" comes into play.
With the information said above, it is now clear how jeweler detectives, antique dealers or scientists use the electromagnetic waves in determining the composition of unknown materials.