Jet is a black fossilized wood, and looks likes coal. It can be used for protection, anti nightmare, luck, divination, and health. It can help to control mood swings and fight deep depression and can be used to dispel fearful thoughts. It is worn or carried to maintain proper energy flow within the body to avoid ill health. 
Jet has been  used as a talisman since Stone Age times, used in olden times to protect from entities of darkness.  Jet draws off negative energy. Those attracted to Jet are said to be old souls.  It can also be used to open to psychic experiences and to assist the quest for spiritual enlightenment.  Jet is said to stabilize finances and protect businesses.  It can be placed in the cash drawer or the wealth corner of the house.  Jet promotes taking control of life. Associated with the base chakra and crown chakra.      
Jet absorbs negativity, and for this reason, needs to be cleansed more frequently than other stones. Clean with warm, soapy water, Do not place in salt water or salt, instead, use a smudge stick to clear it of negativity.

This jet is a very highly polished stone, size 1 to 1.25 inch