Chakra is a Sanskrit word meaning "wheel". 

A chakra is like a vortex:  a constantly revolving wheel of energy. 

These vortexes connect the subtle bodies and act as transducers for life-force energy. The chakras distribute the life force through the physical and subtle bodies.  They are the source of physical, emotional, mental and spiritual energy.   Traditionally, there are seven major chakras associated with the physical body.  They are aligned with the spine and located in the base of the spine, the lower abdomen (sacral), the solar plexus, the heart, the throat, the centre of the forehead (third eye), and the crown of the head.

When our chakras are blocked, or not in balance, the free flow of energy is impeded, leading to physical, emotional, mental or spiritual dis-ease.  When the chakras are unblocked and free-flowing, however, we enjoy optimum health. Each chakra is associated with specific colours and crystals and governs different aspects of human emotion and behaviour.  Using gemstones with the chakras can have a great healing effect.

In Hindu and tantric/yogic, Chakras are energy points or knots in the subtle body. They are located at the physical counterparts of the major plexuses of arteries, veins and nerves. Chakras are part of the subtle body, not the physical body, and as such are the meeting points of the subtle (non-physical) energy channels, called nadiis. Nadiis are channels in the subtle body through which the life force (prana), or vital energy moves. Various scriptural texts and teachings present a different number of chakras. There are many chakras in the subtle human body according to the tantric texts, but there are 7 chakras that are considered to be the most important ones.

Their name derives from the Sanskrit word for "wheel" or "turning", but in the yogic context a better translation of the word is 'vortex or whirlpool'. The concept of chakra features in tantric and yogic traditions of Hinduism and Buddhism.

Amethyst

7th Chakra
Crown Chakra

Amethyst as a healing stone contains sobering and calming qualities which allow this stone to be commonly associated with peace. Amethyst is known to calm and protect the mind. It soothes those who have engaged in constant rigorous mental activity. It has been deemed "nature's tranquilizer" by many healers because of its effectiveness in relaxing not only the mind but also the nervous system. Those who wear amethyst jewellery and who have been recommended to wear this stone for healing purposes have done so because of its tranquil qualities and its ability reduce negativity and alleviate anxiety.

Clear Quartz
7th Chakra
Crown Chakra

Because Clear Quartz has the prismatic ability to vibrate its energy at all of the colour frequencies, it not only harmonizes all of the chakras, but can teach us how to vibrate our seven chakra centres simultaneously while maintaining perfect alignment with the light. Clear Quartz is particularly useful for stimulating the Crown Chakra. The Crown Chakra is located at the top of the head, and is our gateway to the expanded universe beyond our bodies. It controls how we think, and how we respond to the world around us. It is the fountainhead of our beliefs and the source of our spirituality. It connects us to the higher planes of existence and is the source of universal energy and truth. When the Crown is in balance, our energies are in balance. We know our place in the universe and see things as they are. We are unruffled by setbacks, knowing they are an essential part of life.

Tourmaline Quartz
6th Chakra
Brow Chakra

Tourmaline Quartz combines the properties of Tourmaline and Clear Quartz Crystal.  Tourmaline purifies one’s own energies and protects from negativity, while Quartz amplifies energies focused through it.  This combination makes Tourmaline Quartz a powerful shield-stone that, depending on the desired intent of the wearer, can amplify and return negative energy, like a mirror spell, or can convert the negative energy into positive energy for the wearer. Tourmaline Quartz detoxifies the entire body and is used to treat disorders of the digestive tract.

Aventurine
4th Chakra
Heart Chakra

Like most green crystals they are heart chakra stones and will help in the area of love relationships as well. One application where you may use any of the varieties, is to meditate with them, as this may boost your ability to handle life changes. As they contain quartz this will amplify the energy of the inclusion within them during meditation. These green stones have a lovely energy that has the capacity to aid you in releasing anxiety... so using them is a good way to relieve your stress. These crystals are known to also be stones that aid your prosperity. They are known as a stone of luck and will help you to manifest money if that is what you want.

Hematite
3rd Chakra
Solar Plexus Chakra

Hematite is used to improve relationships. If you need your personal relationship to be better, carry a hematite with you always. The name comes from the Greek word for blood. It has been used as an amulet against bleeding, and so is known as the "blood stone". When arranged like the petals of a flower, it is referred to as the "iron rose". Native American folklore states that war paint made from hematite will make one invincible in battle. Scientists of the Mars Exploration Rover Project believe that deposits of hematite on Mars may help prove whether large amounts of liquid water ever flowed on Mars' surface. They say that where water was, life may have had a chance to thrive as well. Hematite is good for increasing intuition. Hematite stimulates iron absorption in the small intestine, which in turn improves oxygen supply to the body. It can be in direct contact with the skin, but results in inflammation for some people, so test it carefully on yourself before use.

Red Jasper
1st / 2nd Chakra
Root Chakra
Sacral Chakra

A strong protection gemstone, red jasper is known to protect against hazards of the night. Red jasper is very lucky for actors. Jasper is one of the oldest known gemstones. It is mentioned in the Bible several times. Jasper is a strong securing gemstone. It is a stability gemstone. It is a powerful protection against things that are not good for you and it eases emotional stresses, making it a wonderful gemstone to have in your home. Jasper gives one the courage to speak out and have personal independence. It also protects from fears in the night. Red jasper is thought to help balance the energy in the body. All jaspers help balance the emotional energy in the body.

Mookaite Jasper
1st Chakra
Root Chakra

Mookaite is an Australian jasper that combines the lighter colours of yellow and red jasper. It encourages the desire for new experiences and helps to keep a balance between external activities and the internal response to these. It imparts a deep calm while encouraging versatility. In Australia, Mookaite was and still is considered to be a healing stone that bestows strength. It is said to shield the wearer from difficult situations and to connect us to loved ones who have passed away. It is believed to bring us into the "here and now," aiding with problem assessment and decision making. Meditation with Mookaite jasper increases your flexibility and your ability to see several solutions to any problem. Mookaite is often used to treat glandular or stomach disorders, hernias, ruptures and water retention, and yoga enthusiasts use it to balance and open the first, second and third chakras.

Blood Marble
1st Chakra
Root Chakra

This mineral is used to provide both clarity and states of "suspension in both meditation and tantric activities. Provides for strength of self-control and mastery of thought. It enhances the powers of serenity. Marble can provide the "good common sense" in matters of the home, heart and one's constitution. Allows for total recall of dreams as well as, provides protection, stability and structure both in the physical and emotional mind. Used very often in the fields of Naturopathy and Homeopathy for its balancing qualities. Ruin Marble provides the additional power of connecting with intellectual states of mind and knowledge.