  Raman spectroscopy is an appealing technique that probes molecular vibrations
in a wide variety of materials with virtually no sample preparation. However,
accurate and reliable Raman measurements are still a challenge and require more
robust and practical calibration methods. We demonstrate the implementation of
a simple low-cost continuous-wave stimulated Raman spectroscopy scheme for
accurate and high-resolution spectroscopy. We perform shot noise limited
continuous-wave stimulated Raman scattering (cwSRS) as well as continuous-wave
coherent anti-Stokes Raman scattering (cwCARS) on polystyrene samples. Our
method enables accurate determination of Raman shifts with an uncertainty below
0.1 cm$^{-1}$. The setup is used for the characterization of reference
materials required for the calibration of Raman spectrometers. Compared with
existing standards, we provide an order of magnitude improvement of the
uncertainty of Raman energy shifts in a polystyrene reference material.
