Warning This Section Does Contain Spoilers
This is a sterling silver stallion necklace that was a gift from Sylvia to Jasper that she made him. Sylvia liked the idea of stallions because they are wild and unbridled. Free of the restrictions of man. Maybe that is how she wishes she could view Jasper.
*Note - Various colours of this necklace were sent, both silver and gold, although I don't believe the colour matters.