The seven main chakras

The first chakra is the root chakra (Muladhara chakra). The root chakra is located at the base of the spine. The colour of this chakra is red/black. The root chakra is responsible for grounding, vitality, stability, adaptability and material wishes.
An overactive root chakra can lead to selfishness, a strong survival urge, materialism and recklessness.
An underactive root chakra can lead to poor self-confidence, unsteady behavior, not being grounded, desire for death, low self-esteem, lack of activity, blood circulatory problems (too high/low blood pressure), depression, anaemia, eating disorders (anorexia nervosa, bulimia nervosa), lower back stiffness and constipation. The adrenal glands are associated with this chakra.
Gemstones associated with the root chakra: magnetite, black tourmaline, res jasper, hematite, obsidian, black onyx, smoky quartz and red garnet.

The second chakra is the sacral chakra (Svadisthana chakra). This chakra is located just below the navel. The colour of this chakra is orange. The sacral chakra is connected with feelings, emotions, creativity, self-confidence and sexuality. An overactive sacral chakra can lead to an overactive sex drive, manipulation and an extreme sensitivity to the emotions of others. An underactive sacral chakra can lead to emotional blockage, exhaustion, fatigue, menstrual disorders (including PMS), bladder problems, a stiff lower back and an aversion to sex. The ovaries and testicles are associated with this chakra.
Gemstones associated with the sacral chakra: carnelian, coral, orange sapphire, brown jasper, agate, fire opal and tiger's eye.

The third chakra is the solar plexus chakra (Manipura chakra). The solar plexus is located in the upper abdomen, just above the navel. The colour of this chakra is yellow/golden yellow. Paranormal impressions enter this chakra.
A balanced solar plexus chakra provides a balance between the mind, intuition and paranormal abilities. An overactive solar plexus chakra can lead to nervousness, restlessness, digestive problems, eating disorders and instability. An underactive solar plexus chakra can lead to apathy, fatigue, obesity, a decreased intuition, anxiety, insecurity, depression, changing moods, digestive problems and diabetes mellitus. The pancreas and adrenal glands are associated with this chakra.
Gemstones associated with the solar plexus chakra: yellow topaz, yellow beryl, barnstone (amber), citrine and tiger's eye.

The fourth chakra is the heart chakra (Anahata chakra). The heart chakra is located at the sternum, in the heart area. The colour of this chakra is pink and/or green. The heart chakra is the chakra of love and compassion. An overactive heart chakra can lead to excessive helpfulness. An underactive heart chakra can lead to love troubles, heart problems, lung diseases and a lack of empathy. The thymus is associated with this chakra. This gland produces growth hormones and affects the immune system.
Gemstones associated with the heart chakra: green jade, smaragd (emerald), peridot, labradorite, chrysoprase, green aventurine, green tourmaline, malachite, heliotrope, rose quartz and rhodochrosite.