HgTe colloidal quantum dots represent an emerging class of nanomaterials with tunable optical properties in the short-wave infrared region, making them suitable for applications in imaging, optoelectronics, and sensing. In this thesis, the optical behavior of HgTe QDs was investigated through the experimental determination of their molar extinction coefficient, a parameter that relates the measured absorbance to the absolute number of nanocrystals in solution. To obtain a reliable quantification, a combined approach was employed, integrating UV–vis absorption spectroscopy, X-ray diffraction, and inductively coupled plasma mass spectrometry elemental analysis. This methodology enabled a direct correlation between structural properties, elemental composition, and optical response.