shine like a diamond in the sky

Diamonds are only chunks of coal
That stuck to their jobs, you see;
If they’d petered out, as most of us do,
Where would the diamonds be?
It isn’t the fact of making a start,
It’s the sticking that counts. I’ll say,
It’s the fellow that knows not the meaning of fail,
But hammers and hammers away.
Whenever you think you’ve come to the end,
And you’re beaten as bad as can be,
Remember that diamonds are chunks of coal,
That stuck to their jobs, you see.

by Virgina Call