The Raman spectra of polymethylmethacrylate (PMMA)/SAN17 nanolayered composite material are used to retrieve the volumetric refractive index of a manufactured gradient index (GRIN) lens. A series of five PMMA/SAN17 nanolayered composite sheets with varying PMMA to SAN17 filling fraction ratios of 0/100, 25/75, 50/50, 75/25, and 100/0 were constructed to calibrate the 785-nm Raman measurement. An additive model was then used to extrapolate the volumetric refractive index profile of the fabricated GRIN lens based on PMMA/SAN17 filling fraction. A good overall agreement between the calculated and modeled GRIN profiles can be observed with an error of ±0.003.