How to tell - Toughened Safety Glass!
“Toughened” or “tempered” or simply “safety” glass is, as these names suggest,
much more resistant to knocks and bumps than regular glass. It is manufactured by
way of a slower cooling process, and as a result, is considerably more robust than
standard panes of glass.

But how would you determine whether a pane of glass is?
“regular” or tempered safety glass?
Of course, the “proof is in the pudding”, in that, if you smash it, it will fracture into
thousands of tiny pieces and remain, as far as possible, in the shape of the pane.
But this is not a practical or advisable way of answering this quandary. So how else
can you tell 

Safety mark

This is the most straightforward way of working out if a pane is made of safety glass
or not. The manufacturer’s logo and name should be present, alongside reference
to the relevant product standard. In the UK, these standards are:
BS EN 14449 – to identify laminated glass (annealed)
BS EN 12150 – to identify as toughened glass
BS EN 14179 – to identify heat soaked, thermally toughened glass.