1. A system for evaluating the performance of a particle detecting and measuring instrument wherein said instrument receives a specimen and detects the number of particles on said specimen and measures the descriptive parameters of said particles, said system comprising: a known specimen received by said instrument and wherein said known specimen has known particles on said specimen, with known parameters of each said known particle on said specimen; said instrument detecting said known particles and measuring the parameters thereof; a matching of individual said measured particles against individual said known particles by means of selected known parameters thereof; a comparison of said parameters of each said measured particle against said parameters of said known particle to which said measured particle was matched; and an indication provided of said instrument's performance as a function of said matching and said comparison.