You should keep it and they should all respect that it is yours. If it was something that could be divided that is different, but it is one object. I think you should keep lending it to other people in the family though, that's a nice tradition.
My grandmother had about 12 diamond rings. She made no mention of them in her Will. Her daughters (my aunts) collected them from the house and shared them between themselves without asking anyone. My father and uncle (the two sons in the family) were left out, I suppose because my aunts thought the jewels should go to the daughters.
My sister and I decided to respect that and not make a fuss, but I admit I do find it annoying when I see my grandmothers rings on my cousins' fingers. It's not the monetary value, I would never have sold one nor cared if I received a tiny diamond or a large one, but the sentimental value. I think if they were to end up with my grandmother's granddaughters (my aunts are alive and well, they chose to distribute them among their own daughters) then I am sure my grandmother would have expected them to be shared equally between us, regardless of whether we were a child of a son or her daughter.
But I think we have a choice in these matters whether to get offended and dig in, risking a family dispute. Or just cop it on the chin and move on. I am sure the last thing my grandmother would have wanted was a family rift. I imagine your ancestors would feel the same.
Anyway, a very long winded way to say- remember what's really important and be as gracious as possible.