First thing to do with this dream is distinguish if it is a fear from seeing terror or horror movie or information that lead us to being frightened. If not then it refers to a real insecurity or fear of something that concerns us. If dreams of fear occur very often, it would be advisable to consult a specialist as it may reflect nerve imbalances that certainly can be treated properly.
Dream dictionary: Fear, Terror dream meanings
…(Dismay | Fright | Terror) In a dream, fear means the opposite. In fact, fear in a dream represents peacefulness and repentance in wakefulness. If one sees himself scared and running away from fear in a dream, it means that he will win the upper hand. If one sees himself in a dream waiting to battle with fear, it means that he will join a war. If one sees himself afraid, and if a voice says to him – “Do not be afraid, you will not die, nor will you be able to bear this life,” it means that he may become blind. If one sees himself as a God-fearing person in a dream, it means that his worldly fears will dissipate and he will develop true devotion and constant remembrance of his Lord. The person or object causing fear in the dream represents harm and aversion. To feel…
Emerald is the stone of secret knowledge. If the dream is accompanied by pleasurable feelings, it expresses the deep desire to acquire knowledge and achieve the gifts of clairvoyance. It can also foretell enjoying perfect eyesight to old age. If accompanied by feeling of anxiety or terror, it reflects the fear of revival of our bad instincts, especially if the emerald is accompanied by a sapphire. It can also foretell an eye disease.