What are the applicable dyes for amyloid metachromasia?

While methyl violets, including crystal violet, are known for metachromatic staining, they are not typically considered the most effective for amyloid metachromasia. Toluidine blue and azure dyes are generally more effective, except in the case of amyloid, where crystal violet or methyl violet can produce significant metachromasia despite not being the primary choice for demonstrating this phenomenon. 

This metachromatic effect in amyloid staining with crystal violet is not primarily due to its interaction with acid mucopolysaccharides but rather appears to result from hydrogen bonding and the regular alignment of dye molecules. The visual result is a distinct deep red-purple color on a blue background, which can vary in intensity based on the mounting medium used. While alternative staining methods for amyloid exist, crystal violet metachromasia remains valuable in cases where other methods may fail to adequately stain amyloid deposits, as amyloid itself is so variable.