Cariad, Just a little something for you to count the hours by. I know Rose will get you to the church rooftop on time, and the Doctors have promised to try and prevent an apocalypse today. I am the happiest man alive for today I get to marry you.
You are my everything, Jack, and worth everything to me.
I love you. -Ianto
p.s.- Yes, it's fully functional and no alien tech. I actually had the parts swapped up for something more durable and better at keeping time, but I thought you'd enjoy the case.
Next to the note is a blue velvet box which contains the following:
The inside of the watch is engraved with: "Though lovers be lost, love shall not."