BZP forms small, colorless square plates in the drop with the platinic chloride reagent. These plates can also be observed on the edges of drop with deformations. The size of the plates differs depending on if 10% hydrochloric acid or 10% acetic acid was used to make the BZP test solution. Platinic chloride reagent by itself crystallizes as square plates on standing. They appear very similar to the drug-reagent crystal observed in this test. However, the drug-reagent plates can be differentiated from the reagent crystals under crossed polars. The reagent crystals are dark or faintly visible under crossed polars while the drug-reagent crystals appear bright white or yellow.