Using femtosecond laser pulses delivered through an optical contact with a highly refractive zinc sulfide immersion medium, a readable photoluminescent micromark was written in the bulk of diamond. The influence of a highly refractive immersion medium on the position and size of the confocal region when reading a luminescent micromark is shown. It was established that in the materials under study the main mechanism of nonlinear attenuation of laser radiation is moderate two-photon absorption, the coefficients of which have been determined. The applicability of zinc sulfide as an optically consistent, highly refractive immersion medium for laser writing and reading of photoluminescent diamond micromarks has been demonstrated. After pressing the diamond into a zinc sulfide plate by high-temperature plastic deformation in an argon atmosphere, optical spectrophotometry and X-ray phase analysis reveal a noticeable opacity of the immersion material due to surface pyrohydrolysis, which partially impedes the read out of photoluminescent micromarks.