Is a pyrylium ring aromatic? I am trying to figure out which rings in callistephin are aromatic:



I know that the benzene rings definitely are aromatic, but I'm not sure about the ring with the positively charged oxygen (highlighted in red).

How does the Hückel $4n+2$ rule apply to this ring?
Pyrylium is aromatic. Following Hückel's rule, pyrylium is uninterrupted (no $\mathrm{sp^3}$ hybridization), all atoms have p-orbitals and there is 6 π electrons. the 6 π electrons indicate that Hückel's rule $(4n+2)$ is agreeable for pyrylium, $n = 1$.