Thermochromic gemstone evaluation using temperature controlled in situ absorption spectroscopy

Thermochromic gemstones exhibit fascinating color-changing properties in response to variations in temperature and light exposure. However, limitations in current experimental techniques for the analysis of thermochromic and photochromic minerals mean that the underlying defects and mechanisms responsible for the effects remain largely unknown. To address this gap, we present an in situ absorption spectroscopy system that integrates precise temperature control with external illumination for real-time absorption monitoring. This system can detect subtle and rapid color changes in both faceted and rough gemstones caused by thermochromic and photochromic responses. In this study, we examine the renowned color-changing chameleon diamond and its cousin, the yellow 480 nm band diamond, to demonstrate the system's capabilities. Our findings provide valuable insight into the mechanisms that drive thermochromic color changes. In addition, this system offers an alternative approach to studying the optical responses of materials under different excitation energies and temperatures, facilitating a deeper understanding of associated optical defects.