To achieve the mirror material you can follow one of the three Methods.
1. Deactivate Fresnel
For this method you are simply going to use raw reflection and remove the Fresnel feature from your properties.
Under the General Tab, Click the “M” beside reflection to access the Vray texture editor. To the Left, you will select the drop down menu and select “none” and press OK.
Go ahead and render your material.
2. Switching Parallel Color
For this method you are going to change the parallel color in your fresnel setting to white.
Under the General Tab, Click the “M” beside reflection to access the Vray texture editor. To the Left, the drop down menu should have "Fresnel" select. You will see the both perpendicular and parallel color option. Change the parallel to white, press OK.