From CRYSTAL MUSE by Heather Askinosie and Timmi Jandro:
Someone new to the crystal world may think the way a stone is cut or shaped is purely aesthetic, but there's a little more to a crystal's shape than meets the eye. While it won't change the type of energy that a crystal gives off, the way a crystal is cut can affect and even enhance how you experience that energy.
TUMBLED STONES: Tumbled stones are a great place to start your crystal adventure. For a small investment, the benefits you will receive from these pocket-sized crystals are significant. We have found that many of our clients will work with a different stone every day, one that they resonate with that acts as their 'daily energy prescription.' Because of their size, tumbled stones can be put in your pocket or in your bra, displayed on your office desk, placed inside your car, or tucked under your pillow.
SPHERES: Crystal spheres allow energy to emit in all directions. The perfect symmetry of a sphere brings balance, peace, and relaxing energies into its environment. Meditating with a sphere provides a deep sense of wholeness, as if you hold the world in the palm of your hand. They unite all parts of your being and connect you with the energy of your surroundings.
PYRAMIDS: Pyramids are one of the most powerful tools for both manifesting and amplifying energy. This sacred shape has been used by many ancient civilizations, none more famously than the ancient Egyptians. They believed that pyramids symbolized the rays of the Sun. Crystals in this sacred shape are thought to harness high vibrational energies for greater manifestation power.
HARMONIZERS: Crystal harmonizers are polished into cylindrical shapes for holding during meditation. These crystal tools have been crafted for curing energy blocks and energetic imbalances since the time of the ancient Egyptians. By holding one harmonizer in the left hand (yin) and one in the right (yang), spiritual vitality is reinvigorated, and sense of balance can be restored.
CUBES: Many crystals are found in a cubic formation. The cube shape is associated with the root chakra. Meditating with cubic crystals will help to ground your energy and reconnect you with the powerful energy of the Earth. By placing cubic formations in each of the four corners of a room, you will seal, protect, and ground the energy of your space.
HEARTS: Heart-shaped crystals remind you that you are always surrounded by love. They are powerful allies in helping to attract love from others, as well as nourishing yourself with love from within.
POINTS: Crystal points are one of the most commonly used and beneficial shapes to work with. They are very powerful for manifestation, as they help to manifest your dreams, wishes, and intentions at a much faster rate by directing your intention up into the universe.
CLUSTERS: A crystal cluster occurs when several crystal points grow together on a matrix. Due to the convergence of many crystal points, a crystal cluster vibrates at an even higher energy, directing energy in multiple directions and making it a crystal essential to have in any space.