What Is a Gem

Gems are often characterized as expensive sparkling stones. The value is not necessarily as obvious as we might hope. Even so, you will probably spend significant money on gems. A gem can be real (natural), synthetic (grown in the laboratory or factory), or a simulant (one material made to look like another). 

The scientist s way is to use X-ray diffraction (XRD), X-ray energy-dispersive spectrometry (XEDS), wavelength-dispersive spectroscopy (WDS), or comparable techniques for chemical analysis. 

The gemologist s way is to use the refractive index or the thermal and/or electrical conductivity. 

The difference, of course, is that the gemologist must often identify the gemstone in the field (in the home, in the mine, or really in the field) without taking the sample to the laboratory. With experience, you can, for example, feef if a stone is a good thermal conductor. 

The questions emphasize the need for techniques to aid the eye in examining these materials, or the need to understand the structure and chemistry of gemstones when handling them. 

---