It is a jewel which has the same planetary influence as Mercury. Mercury in Aries rashi is the lord of 2nd and 6th in auspicious house. So, wearing emerald will be harmful for you.
Mercury in Taurus rashi is the Lord of 2nd and 5th Trikon and Venus the Lagna lord is an ally. For family peace, wealth gain, intelligence, happiness from the children. You can also wear it for name, fame and esteem and for good luck.
Mercury in Cancer rashi is the lord of 3rd and 12th inauspicious bhavs. So, emerald will be harmful for you.
Mercury in Leo rashi is the lord of 2nd and 11th bhava. You will get happiness from children, family happiness + abundant wealth provided you wear emerald in the dasa of mercury.
Mercury in Virgo rashi is the lord of Lagna nad of its 10th Kendra.Emerald will ensure your good health.
Mercury in Libra rashi is the lord of 9th and 12th bhava. Emerald will boost your progress and luck.
Mercury in Scorpio rashi in the lord of 8th and 11th bhavas and Mars the Lagna lord is its enemy. You will be gain economically, if you wear emerald in the dasa of Mercury.
Mercury in Sagittarius rashi is the lord of the 7th and 10th house and Jupiter is the Lagna lord. Emerald will be harmful for you.
Mercury in Capricorn rashi is the lord of 6th and 9th house and is an ally of the Lagna lord.
Jupiter in the 9th bhava, its basic trikon rashi is also there. Emerald will be favorable and propitious for you.
Mercury in Aquarius rashi is the lord of pancham trikon and 8th house; and Saturn the Lagna Lord is its ally.Emerald will be favorable for you.
Mercury in Pisces rashi is the lord of 4th Kendra and 7th kendra bhava. Wear emerald in the dasa of Mercury, only after seeking proper advice.