yearofjohnlock: Moriarty places a diamond in the middle of this message: which allowed him to...

Moriarty places a diamond in the middle of this message:

which allowed him to shatter protective glass. I always associated the diamond with John, much like Magnussen’s reading of pressure points on Sherlock. But the diamond is the engagement & wedding specifically, and more specifically the bride.

Shattered glass at a wedding

We also see glass shatter another time in reference to a bride:
Sherlock’s shattering comes through a bride, but perhaps we do not know if Moriarty implanted the bride (MARY) or if the bride implanted Moriarty.

Shattered glass means the reveal, the discovery all three cases immediately preceded solving a crime. It is another curtain or veil-rising analogy. Just another magic trick.