A gold medallion of a triggerfish is nestled in the collar of his shirt. (inc.com)
Thinking you could also save and (with some finishing on the cut edge) wear the collar of the shirt like a choker to complement the dress, especially if it's one of those men's shirts where the collar is a different colour / pattern from the body of the shirt. (apairandasparediy.com)
Wear a statement necklace in an open neckline, under the collar of a shirt, with a high neckline like a turtleneck or bateau, or with embellishments like a ruffled collar or sequin top. (yourtrueselfblog.com)