Standard shader strange reflection artefacts

I'm trying to create a glass material. The way I configured it is the following:

Shader: Standard shader (specular) Rendering Mode: Transparent Albedo: black color with 90 in alpha Specular: very dark grey with a value of 35 Smoothness: 1

I'm getting something like this on iOS for a nearly flat surface:

In the editor it shows up as a white pixel at the same average position. The white dot is due to the directional light reflecting off the surface. This dot becomes a blurred disc when you lower the Smoothness value. On iOS a lower value produce the same sort of artefacts even if those are less visible. I first used that as a workaround but it doesn't produce the best effect.

Is there a way to prevent this reflection dot/spot/disc from happening?

I have actually got the same result with a non-transparent material some times ago. It seems to be happening every time I use standard shader, but is most visible in the case smoothness is set to 1.

By the way I'm using Unity 5.0.1, OpenGL in the editor as I'm on Mac OS and OpenGL ES 3 on the targetted device.

Thank you for your help!

EDIT: Sorry for the duplicate! I got some answer on the forum: http://forum.unity3d.com/threads/standard-shader-material-directional-light-reflection-creates-big-white-artefacts-on-ios.322624/