A 1mm deep scratch is one hell of a scratch to cut back to - especially in safety glass. You cant cut this etc - it just shatters... its tempered once its cut.
What you can do though is minimise the damage. If you run some spit along it with your finger youll notice it fades out a bit. Thats because the edges of the scratch are rough and so deflect light. if you run some clear glue like super glue or clear nail varnish into the scratch itll be less noticeable. Really all you need to do is smooth off the rough edges of the scratch
