Direct numerical simulation of mixing processes (Rayleigh-Taylor and Richtmyer-Meshkov instabilities) is computationally expensive due to the need to resolve turbulent structures on small scales. Hence, it is common practice in both academia and industry to use phenomenological models that explicitly model the mixing processes within a host hydrodynamic code. For such schemes to be self-consistent, the mixing should be dominated by the mass introduced by the dedicated mixing model, with minimal contribution from the numerical methods of the host code. In this report, several diagnostic statistics are described that allow for the assessment of the production of mix and a determination of the quality of a mixing model. These diagnostics are implemented within an existing two-dimensional finite element hydrocode, containing an implementation of Youngs' turbulent mix model, and used to assess the mixing scheme against a number of two-fluid test problems.