The trinket was an anniversary gift from the 32-year-old Scottish DJ, which commemorated their first year together as a couple. The locket features an engraving of the date "3-6-2015," which is the date they officially became an item.
Swift shared a close-up Instagram photo of the locket on Sunday after Harris posted a Snapchat, sharing how they spent their special day.
In the nine-second video clip, which shows a chocolate cake frosted with the words "1 year" and two red hearts, the DJ/music producer excitedly says, "One year, we got one-year cake!" as the "New Romantics" singer smiles and nods.