Tag implication:
Reasons:
- Both tags are the same thing, except one is restricted by quantity (a single earring) and the other is not (any number of earrings).
- The wiki of earrings has this note since 2009, emphasis mine: "If you're sure the character is wearing only one earring, you should additionally tag the image with single_earring."
- The search single earring earrings returns 243 results.
- The search single earring -earrings returns 217 results.
Updated by NWF Renim