Systems and methods for non-invasive material analysis are disclosed in which a material (e.g., a liquid such as blood) is illuminated at a plurality of discrete wavelengths. Measurements of the intensity of reflected light at such wavelengths are taken, and an analysis of reflection ratios for various wavelengths is performed. Changes in the reflection ratios can be correlated with specific material properties such as the concentration of analytes (e.g., oxygen content, glucose levels, cholesterol or drugs in a subject's circulatory system).