This cell is colorless or translucent they have granule- like materials that’s why they appear to be white and also with the use of eosin (an acidic staining material) they may appear red to pinkish-orange. Hematoxylin (a basic stain) they may appear blue to purple in color.
Basophil- granules may stain blue or purple with basic dyes
Eosinophil- granules may appear bright red when stained with eosin.
Neutrophil- may appear light-pink to bluish purple when dyed with acidic or basic dye.
Lymphocyte-bluish cytoplasm purple-ish when basic dye is used
Monocyte-dull blue- gray cytoplasm purple-ish when basic dye is usedhttp://www.uwosh.edu/med_tech/what-is-elementary-hematology/white-blood-cells
You can also refer to the book of Mader and Windlespecht (Biology 11th ed.) or Anatomy and Physiology of G. Tortora