Mercury is the planet of intellect and communication and its gemstone is Emerald.

The energy of Mercury is neutral, emotional, joyful, and evergreen. It is recognized by its ready wit, wisdom, and power of communication. It can be quick-changing and fickle.

The energy of Mercury makes people flexible (both physically and mentally), skillful, clever, and delicate. 

Emerald is good for writers, lecturers, artists, teachers and those associated with education, traders, and businessmen.a

Emerald is good for the nervous system, lungs and respiratory system and the intestines. It is also good for intelligence, speech, self-confidence, humor, and wit.

Substitute gemstones for Emerald are Aquamarine, Peridot, Green Zircon and Green Tourmaline.

The energy of Emerald gives one good health. Apart from this, it also makes one wise and intelligent. It increases ones wealth and property and blesses one with children. It gives protection from the bites of slithering creatures such as snakes, it also protects one from  influences of evil. It is also considered beneficial for the eyes. This gemstone helps one in getting rid of insomnia and depression.

Those suffering from the following with benefit from the energy of Emerald: Chronic dysentery, constipation, lack of digestive fire, lung diseases, asthma, restlessness, kidney problems, fear, neurosis, and madness.

Here is a Nice Little Kundalini Yoga Kriya to do to Enhance Your Intellect and Communication.