My Well Thoughtout soon to be Crime...

Only when the sirens have sound,
I shall commit a legendary crime...
Talked about throughout the land,
It would be my final, my only grand-plan.
It will be a design of no other,
I shall rethink this rebellious state towards my mother.
But that is too far ahead to see...
What is my scheme?
What is my jewel?
It is a diamond that seems to gleam
A fight, between a master and an apprentice,
A fight to death, a deadly dual...
The master; a man of many sorts,
A personality that would fit five beings,
When he thieves, you won't believe what you are seeing...
He had once disowned me,
But now he will drown
This will be!
I shall take the thing you always lusted,
The Cullinan,
It sits in a crown jewel, infested.
Its beauty bedims our minds,
Loss of thought is caused, this I find!
But what is my plan,
Well there is none,
As if I could think of one...
No I just enjoyed my little rhyme,
Maybe I will think of a crime to land,
Only in good time!