Metaphysically speaking, a “vibration” can be thought of as a projected concept or sense, an emanation of the collective consciousness. For example, rose quartz is generally associated with the concept of “love;” therefore it has a “vibration” of “love,” which is considered positive (as opposed to fear, which is considered negative).

Love is not currently something that can be accounted for using physical scientific exploration alone. To be sure, the biochemical aspect of love is being studied and decoded (e.g. hormones and neurotransmitters), and the perception and psychological impacts of love (or the lack thereof) are another part of the investigation. However, these inquiries are only revealing part of the nature of love: body and (partially) mind and emotion. The spiritual, intuitive and unquantifiable aspects of love, the “essence” of love (and other concepts, e.g. fear) are more the province of metaphysical language.

Metaphysical lexicon (much to my left brain’s chagrin) is imprecise because it is essentially borrowed from language used primarily to describe physical phenomenon.

I hope this is helpful.