Negative energy makes you, your physical body, or your surroundings feel heavy.  Cleansing these energies with crystals brings instant lightness.  Black stones absorb negative energy while other colors stimulate positive energy.  Here are some examples:  Smoky Quartz varies in color from light brown to almost black.  It makes a perfect grounding stone because it is attuned to the earth.  It has the ability to neutralize personal and environmental negative energies.   Green Calcite is a translucent, waxy stone that clears negativity out of a stagnant situation, and helps with adjustment to new challenges.  Chalcedony encourages introspection.  It gently releases self-doubt and negative beliefs, creating a new enthusiasm.  It has the ability to absorb and dissipate negative energy.  A powerful cleanser of energy, it is one of the few crystals that does not always have to be cleaned after use.  Jade comes in several colors and each has specific properties.  All colors of Jade share the ability to release negative thoughts and energies.  Jet is hard, fossilized wood.  Jet is a powerful absorber of negative energy.  It overcomes unreasonable fears, creating a more powerful outlook.  Apache Tear is translucent, water-smoothed and provides an excellent remedy against negative energy from any source, but especially against the negativity of other people.  The energy is absorbed and then sent to the "rubbish dimension."  Citrine is a clear yellow to brownish-amber Quartz and has the ability to dissipate and transmute negative energies without absorbing them and can be used without cleaning.  Citrine dispels negative feelings and aids in accepting constructive criticism.  Amber is an excellent energy cleanser, drawing negative energy from the body and allowing it to heal itself.  It also clears environmental energies.   Source: The Illustrated Guide to Crystals by Judy Hall.