Celestine Blue Iron Alum Solution is an in vitro diagnostic agent specifically designed for use in HEROVICI staining for collagen differentiation, helping to distinguish different stages of collagen in tissue samples.

Coelestine Blue B, a basic dye, binds to the acidic components of the extracellular matrix, enabling the staining of collagen fibers. Ammonium iron (III) sulfate acts as a mordant to enhance the binding of the dye. After application of the solution, younger collagen (type III) shows up in red and more mature collagen (type I) in blue. This differentiated display supports the diagnosis of various tissue changes, such as those that occur in inflammatory or fibrotic processes.