With a ragged diamond of plate glass.”
The first two lines of the poem appeals to the reader a metaphor “ragged diamond.”
The use of the word ragged to describe the glass suggests something broken or torn.

The second image is of “a young man and his girl falling backwards into a shop-window.”
This is written in the present tense.
The reason for this is to create a sense of immediacy.
This gives the reader a sense of almost being a witness to this event.

The next image in the poem is a violent one “The young man’s face is bristling with fragments of glass” it is as if the man has a beard made of glass.
The use of the word “bristling” shows us that the man has fragments of glass puncturing his face.
The reader is then left to wonder how the glass came to be stuck to his face.
The comparison with a beard is deliberately ironic and shocking.

“and the girl’s leg has caught on the broken window”
The poet’s choice of words is very important here. “Caught” suggests something that has trapped the girls leg is trapped by the shattered plate glass and she is probably seriously injured.
The poet draws even more attention to the violent detail,
“And spurts arterial blood over her wet-look white coat.
The poet used both sound imagery “spurts”, and visual imagery. The implication of the bloods colour is suggested by the word arterial. Clearly an artery has been cut which puts the girl in grave danger. “
This contrast with the white coat again drawing attention the blood.

The poet also uses image of helplessness “Their arms are star fished out braced for impact”, the image of a starfish reinforces the idea of them being helpless.

“The two youths who have pushed them are about to complete the operation”
The key word here is “operation” I think the poet chose this word because it shows that the youths had planned for this moment.
The connotation of the word “operation” is that they done it precisely, deliberate and without care for the victims. The poet takes this further by showing the caloses attitude of these two youths.

“Reaching in to the shop window to loot what they can smartly”
Again the word choice is important. The use of loot suggests that thing have been stolen.
Further the word “smartly” makes it shocking because we don’t usually suggest smart people to commit violence.
The reader is incredibly shocked by the two youths body language “their faces show no expression” The two youth’s reaction to what has happened is not normal human behaviour. It is in direct contrast with the reader, who is shocked, horrified and probably angry at, this callous behaviour.

So despite all the broken glass, despite all the blood and despite the two people lying in a lot of pain and distress.

“It is a sharp clear night in Sauchiehall Street” the poet makes reference to the visual.