Diamond grading mechanism with collimator - measures reverse facets of diamonds by reflecting filament cross projected on screen

摘要

The diamond grading mechanism comprises an automatic collimator (8) contg. in its radiation path a holder (17) for a diamond (14) or brilliant. A filament cross is reflected by the reverse facets of the diamond onto a receiver screen and the deviations between the reflection images and the different pairs of reverse facets are measured. The reflection images are produced by using a brilliant from diamonds having a reverse facet angle of more than 39.8 deg. A measuring coordinate image is pref. mounted in the eyepiece of the collimator (8).