We present a magic frequency associated with two-photon processes in room temperature atomic vapour at the coherent population trapping (CPT) condition for an elliptically polarized light. It is realized by combining the symmetries of the line shape functions arising from the atomic coherence. In practice, the magic frequency is synthesized from a polarimetric measurement involving the reflected and transmitted CPT signal at the polarizing beam splitter, which provides an atomic frequency standard for near zero magnetic fields. We further develop a magnetometer, which concurrently measures the magnetic field and its direction from the enhanced reflected signal with significantly improved performance. Additionally, the magic frequency and its dependence on the polarization content provide a handle to precisely locate the single photon resonance.