Clusters of thin, orange plates are observed with the gold bromide reagent. The orange crystals are not easily visualized in uncrossed polars because of low contrast with the reagent. However, the crystals are bright under crossed polars and the characteristic clusters of plates can be observed. This reagent is the best reagent for characterizing α-PVP and forms crystals reliably. The crystals however are very light and though infrared spectra can be obtained, the spectra are very noisy and signal intensity is low.