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Iridophores, dermal iridescent cells of cephalopods, are used in camouflage and communication. Squid of the Loliginidae family have unique iridophores which are dynamically tunable, meaning the squid are able to quickly control the activation of the cells as well as the color being reflected. Understanding the properties and mechanisms utilized by the tunable iridophores will assist in the development of synthetic, tunable, iridescent materials. The cells are known to have the structure of multilayer Bragg reflectors, however, the exact mechanisms involved in their tunability are not entirely understood. We determined the refractive index of reflectins, proteins within the iridophores. To do this, we used fixed tissue of L. Opalescens, taking spectra of the same cells before and after the extracellular fluid was exchanged for one of a higher index of refraction. As expected the reflectivity of cells decreased as the refractive index of the extracellular fluid was increased. Unexpectedly a blue shift in the color being reflected by the cells occurred after an initial red shift, indicating that the thicknesses of the layers created by the intracellular spaces were changing. This was most likely due to the desiccation of the cells by the increasing osmolarity of the extracellular fluid, an issue which is currently being addressed. Initial modeling of the cells with water as the extracellular fluid, indicates a refractive index of the reflectins ranging from 1.39 to 1.45. After addressing the osmolarity issue, we hope to confirm this range of refractive indices and to determine if they correlate with the color of the light being reflected.