Gram staining is a method of differentiating bacterial species and it is commonly known and used in microbiology. It is also one of the most frequently used diagnostic methods in hospitals and clinical laboratories. Gram staining differentiates bacteria into two groups: Gram-positive and Gram-negative. That division is based on the two groups’ bacterial membrane structural differences, i. e. their capability of retaining the dye. BioGnost’s Fuchsin Basic reagent is used for contrast staining of bacterial species that did not retain their primary dye, i. e. Gram-negative bacteria. That enables differentiating the blue and purple-colored Gram-positive bacteria from the red-colored Gram-negative bacteria.