The monetary value of jewelry is largely determined by the content of precious metals in the alloy and the type and quality of gems. Design and workmanship play a less important role.
There are several methods for alloy analysis, the oldest and most accurate one is fire assay. This method uses the high accuracy and precision of balances to weigh a piece of the original metal. Then, the non-precious metals in it are removed by different procedures (oxidation and dissolution) and the residue is weighed again. This is a destructive analysis that damages the jewelry though. Furthermore, this method is time consuming, generates environmental waste and cannot distinguish between the different elements in the residue, what could lead to misinterpretations of the analytical results.
However, the X-ray fluorescence (XRF) analytical method discussed here offers a contact-free and non-destructive analysis with good accuracy. Since jewelry pieces are often small and intricate, it is also very important to analyze only a small area. This is possible due to the strong collimation of the excitation beam provided by the instrument used here.