A necklace was a piece of jewelry used as a clothing accessory, worn on the neck.
An arm bracelet Christine Chapel owned looked more like a necklace when she shrunk in relation to its size in 2269. (TAS: "The Terratin Incident")
In 2293, Klingon Chancellor Gorkon occasionally wore a silver-colored necklace that his daughter, Azetbur, inherited after Gorkon was assassinated later that year. (Star Trek VI: The Undiscovered Country)
The Ligonian First One Lutan wore a necklace with a red crystal when he was encountered by the USS Enterprise-D in 2364. Yareena, his wife, later removed this necklace and chose Lutan as her second husband when she gave the necklace to Hagon. (TNG: "Code of Honor")
Only four of the Edo encountered by the crew of the Enterprise-D in 2364 wore silver necklaces with the Edo symbol included: the two leaders Liator and Rivan and two mediators. (TNG: "Justice")
In 2364, Anne Jameson wore a necklace while she visited the Enterprise-D with her husband, Admiral Mark Jameson. (TNG: "Too Short A Season")
The Kataan native Eline wore a necklace shaped like the Kataan probe. (TNG: "The Inner Light")
Vash once obtained a gold necklace from a trip she took to the Gamma Quadrant. In 2369, she secured it in a storage locker of the assay office aboard Deep Space 9. (DS9: "Q-Less")
Vash herself wore a necklace which was not put around her neck but attached to her earrings. (TNG: "Qpid"; DS9: "Q-Less")
The Bajoran Kai Opaka gave Miles O'Brien her necklace, including a pendant, shortly before she left Deep Space 9 in 2369. O'Brien gave it to his daughter. (DS9: "Battle Lines")
Later the same year, Arbazan Ambassador Taxco wore a golden necklace during a visit aboard Deep Space 9. (DS9: "The Forsaken")
A necklace was one of numerous items stolen by a Dopterian thief at Quark's. (DS9: "The Forsaken")
In 2370, the Iyaaran ambassador Voval, disguised as Anna, wore a necklace which allowed him to create this illusion, to study the concept of love with Captain Picard. (TNG: "Liaisons")
Caylem gave Captain Kathryn Janeway a necklace formerly owned by his wife believing Janeway was his daughter Ralkana. Later, Janeway accepted to trade this necklace for weapons with Darod after she first refused and only agreed after Caylem told her to do so. (VOY: "Resistance")
In 2375, Starfleet soldier Reese wore a necklace of ketracel-white tubes he took from Jem'Hadar he killed on AR-558. (DS9: "The Siege of AR-558")
Upon arriving on the Hysperian cruiser Monaveen in 2381, Andy Billups was given a necklace by a dancer, which featured large blue gemstones and a pendant in the shape of the ship. (LD: "Where Pleasant Fountains Lie")
In 2399, Dahj Asha possessed a necklace that, at least according to her recollection, was given to her by her father. It was made of a silver-colored material and featured a pendant consisting of two interlocking circles. She left it with Jean-Luc Picard. After her death, Dr. Agnes Jurati recognized the pendant as a symbol of fractal neuronic cloning and speculated that Dahj, whom Picard believed to be an android, had been created through that technique. In the same time period, Soji Asha, whose appearance was identical to Dahj's, wore an identical necklace at the Romulan Reclamation Site. (PIC: "Remembrance") That same year, Dahj discovered that her necklace had been made only thirty-seven months earlier. (PIC: "The Impossible Box")