Diene method is used for

Mycoplasma colonies may be seen with a hand lens but are best studied after staining by the Dienes method. For this, a block of agar containing the colony is cut and placed on a slide. It is covered with a coverslip on which an alcoholic solution of methylene blue and azure has been dried. Ref: Textbook of microbiology; Ananthanarayan paniker's; 10th edition; Pg:394