Tube stopper colors and additives

Gray top

Potassium oxalate
Sodium fluoride

Green top (non gel)

Heparin

Lavender top

EDTA

Light blue top

Sodium citrate

Pink top

EDTA

PPT pearl

EDTA thrixotropic gel

PST

Heparin thrixotropic gel

Red top

Clot activator( silica) or no additive

Royal blue top

No additive heparin EDTA

SST gold

Clot activator(silica) thrixotropic gel

Yellow top (blood bank)

ACD

Yellow top (microbiology)

Sterile SPS