Does hanging a small jar of olive oil from a chain around the neck, for moisturizing and adornment, constitute imitation of non-Muslims?

It is forbidden to wear a necklace if it is a custom specific to disbelievers or polytheists, even if it is for adornment or has a benefit; this is based on the Prophet's (peace and blessings of Allah be upon him) saying: "Whoever imitates a people is one of them." However, if it is not a characteristic specific to disbelievers, then there is no objection to it. The criterion for forbidden imitation is that the action must be exclusive to a particular group and not performed by others.