Painters prefer to work with natural light but will accept a blend of natural, incandescent & fluorescent in some cases. It follows then that once you find the purest color/reflectivity in a mirror, you/it should benefit from similar lighting in order to get a true reflection.
Bathroom vs work lighting should be obvious in differences created by the light "bulbs", not to mention shadows, et al. ... not really candidates but easy to use. Cameras must be out of budget sorts in order to come close to a true mirror setting (above)