My title describes the thing. This item is made of metal adorned with large jewels on either end, likely cubic zirconia or something of that nature. It unscrews at one end. It may be around 100 years old. That’s really all we know.
Jabot pin. Though they were often worn on hats — probably Art Deco era (post-WWI through 1920s)
Think it could be a hat pin. Or a fur pin.
Or, could also be worn on the collar? Like a collar closure.
I think a collar(tie) pin.I have maybe 30 gold plated ones from loooong ago.
Maybe it’s bellybutton piercing?
Looks like it could be a bar shaped piercing for upper ears.
A ‘spic pin’ . Goes through small holes in the collar. One end probably unscrews.
Is it a way to attach a boutonnière perhaps?
It’s a collar tie pin. It holds your collar tabs together neatly when wearing a tie.
Looks like a barbell cufflink.