AbstractNumerous bio‐organisms employ template‐assisted crystallization of molecular solids to yield crystal morphologies with unique optical properties that are difficult to reproduce synthetically. Here, a facile procedure is presented to deposit bio‐inspired birefringent crystals of xanthine derivatives on a template of single‐crystal quartz. Crystalline sheets that are several millimeters in length, several hundred micrometers in width, and 300–600 nm thick, are obtained. The crystal sheets are characterized with a well‐defined orientation both in and out of the substrate plane, giving rise to high optical anisotropy in the plane parallel to the quartz surface, with a refractive index difference Δn ≈ 0.25 and a refractive index along the slow axis of n ≈ 1.7. It is further shown that patterning of the crystalline stripes with a tailored periodic grating leads to a thin organic polarization‐dependent diffractive meta‐surface, opening the door to the fabrication of various optical devices from a platform of small‐molecule based organic dielectric crystals.