lol, I usually base it off a certain color and go from there~
Maybe find pictures, one for spring, one for winter, etc, and then just switch the urls around whenever a season changes?
Sounds a bit large, I was thinking maybe around two inches for the word Antagonist in some fancy slanted swirly font.
And 18 inches for the chain is definitely too long! 12 inches should be enough...*ponders over savings* I keep wanting to buy more necklaces!