Van Gieson's stain is a mixture of picric acid and acid fuchsin. It is the simplest method of differential staining of collagen and other connective tissue. It was introduced to histology by American neuropsychiatrist and pathologist Ira Van Gieson.
HvG stain generally refers to the combination of hematoxylin and Van Giesons stain, but can possibly refer to a combination of hibiscus extract-iron solution and Van Giesons stain.