Genuine OEM Canon PIXMA MG6320 Ink and Supplies
Gray ink is separate from black ink in the MG6320. A CLI-251 four-color pack leaves gray out; the five-ink CLI-251 pack adds it, but neither pack includes the printer's separate PGI-250 pigment-black tank.
Toner Buzz carries genuine Canon PGI-250 and CLI-251 singles, XL inks, black twins and mixed packs, including a CLI-251 pack with gray. Choose a gray single for that ink alone, or check the pack contents when you're ordering several inks together.