Optical sensors have become essential in human health and are progressively being integrated into daily life. However, the impact of skin pigmentation on the effectiveness of these devices still requires thorough investigation. High melanin concentrations are known to significantly affect the performance of optical techniques,such as, medical imaging, photoacoustics, laser therapies, tattoo removal, and even the functionality of optical sensors in smartwatches and biometric systems. Despite these challenges, the use of optical procedures on the skin, regardless of its tone, continues to grow as a promising and in-demand frontier. Therefore, a more comprehensive understanding of light-tissue interactions, employing reproducible and standardized methods, is crucial for improving the efficacy and safety of these procedures. This seminar will explore potential studies and applications of diffuse spectroscopy to address these limitations.