​Black colonies that grow after 48 hours of incubation at 37°C after sowing with the appropriate spreading method are counted as S. aureus.

Coagulase staphylococci (Staphylococcus aureus) bordered, transparent

It produces dark gray to black, glossy convex colonies with or without opaque zones around it.

Coagulase-negative staphylococci grow poorly or not at all in gray to black colonies, often without clear or opaque zones. Organisms other than staphylococci are generally inhibited.

If growth is observed, colonies may be brown to gray or colorless with no clear or opaque zones visible.