Shine, or reflection, determines how strongly the current sky texture
, if the prim
is over water) is blended onto the face
s of the prim. This effect is also known as environmental texture mapping.
Depending on your interpretation of quantum physics, there may exist some alternate universe where it is computationally feasible to make this option actually make the faces of a prim reflect the world around them like a mirror, but due to the design of SL's 3D engine and the constraints of current computing technology, it is not possible in this universe...at this time. Real-time 3D rendering technology is rapidly advancing...
The shininess of a prim can be controlled with llSetPrimitiveParams
Enabling reflection will cause the prim/side
to darken more with each reflection setting (low, medium, high).