Brilliant cresyl blue is more used in hematology laboratories than in histology laboratories. There, it is invaluable for the staining of reticulocytes and platelets whereas its use in histology is limited to vital staining.

This dye is often provided as a half zinc chloride salt, so the difference between the formula weights in the information box is likely due to whether half a zinc chloride molecule has been included in the formula weight of the dye.

Due to manufacturing preferences, there have been two compounds identified using the name Brilliant cresyl blue, both of which appear to stain identically and can be substituted for each other. The compound provided at the present time is formula A, above. Formula B was provided before the second world war and in Europe until a few decades ago. The difference is in the location of the methyl group. Horobin and Kiernan gave four structures, three of which have been manufactured and sold under the Brilliant cresyl blue name.