Cerridwen Greenleaf, author of The Magic of Crystals and Gems, has written a guide on the different types of stone shapes and the positive energy they can all bring to your life.

Ankh-shaped stones represent the key to life. Use this ancient Egyptian symbol to develop creativity, wisdom, and fertility.
Clusters are among the most common natural crystal forms and bring balance and harmony into your life.
Diamond-shaped stones bring the energy of wealth and abundance and are said to attract riches.
Egg-shaped stones denote creativity and give new ideas to anyone wearing them
Heart-shaped stones bring love energy. They promote self-love and romance.
Holes that form naturally in stones are very auspicious and magical. If you look through the holes by the light of the moon, you should see visions and spirits.
Human body-shaped stones bring good energy to the body parts being depicted and strengthen those areas.
Obelisks are four-sided, pyramid-topped shapes and are wonderful energy activators, or manifestors. Write your wish down on paper and place it beneath an obelisk to bring that hope into reality.
Octahedrons, eight-sided stones, bring order to chaos and are great for analysis and organization. They are also terrific for healing. Carry an octahedron crystal in your pocket if you are unwell, so you can feel better soon.
Pyramid-shaped stones carry energy upward, toward their pointed tips. I have a beautiful little malachite pyramid that I keep on my computer simply because I love to look at it. When the need arises, however, I can place a dollar bill underneath it and visualize positive money energy flowing up out of the stone.
Rectangular rocks and crystals represent the energy of God. In addition to symbolizing male energy and the phallus, this shape is symbolic of energy itself and electrical current. It also denotes protection. Rectangular stones are great for love and sex spells.
Round stones represent the universe and the Goddess. They are symbols of spirituality, connection to the universe, femininity, and, of course, pregnancy. Round crystals can be used in all love spells to cause attraction.
Square stones represent the earth and are harbingers of plenty and prosperity.
Triangular stones are guardian stones and protect the wearers.
The magic of crystals and gems
Unlocking the Supernatural Power of Stones (Healing Gemstones and Crystals)
Practice Practical Magic: Did you know that wearing an amulet of green jade on an interview will help get the job? Have you heard that an amethyst ring can help break bad habits and even encourage sobriety? Anyone looking for love can place two pink quartz crystals in the bedroom; you’ll not be alone for long! These are just a few of the hundreds of secrets shared in The Magic of Crystals and Gems. Semi-precious stones and gems have long been known for their magic as well as their beauty. In this book of charms, readers learn everything there is to know about the powers of crystals from birthstone magic to gem divination to jewelry spells. This is a fun, entertaining, and enlightening book that will appeal to everyone who’s ever worn a birthstone, kissed the ring of a lover for luck, or bought a crystal for good energy.