The word "emerald" is derived esmeraude (old French) and emeraude (ME) from Vulgar Latin: esmaralda/esmaraldus, a variant of Latin smaragdus, which originated in Ancient Greek: σμάραγδος(smaragdos; "green gem")

Green is the colour of nature,  calming colour in the wheel. It represents fertility, peace and balance.

It's not a stone for passionate love,  but it's a symbol of hope.

The emerald is the sacred stone of the goddess Venus. 

It was thought to preserve love

Emerald opens and nurtures the heart and the Heart Chakra

It was found on the breastplates of the Kings & Queens in the ancient times.