Go to the supermarket and pick up a storage box, some tape and greaseproof paper. Line the two sides and the top of the box (box opening facing you) with greaseproof paper and tape a sheet of A4 paper (or greaseproof if you're really on the cheap - you have a roll of it) to the top-back of the box, with it curving down and towards you.
You may need to put it on a book or something if the shape of the box is odd.
What a light box does is flood the object inside with flat, even light, so all that you need to do is point all the lights you can find at the outsides and light up the paper. If you don't have any lights, you can put it in a window, on the balcony or under your strip lighting. As long as the light inside the box is flat and even, it doesn't matter.
Once the light is bouncing around inside, point your canera at the white paper and set the white balance. Then, put a watch in and snap away. It'll take some getting used to, but you should end up with results like this, especially if you have a polarising filter on the camera set to 90deg to the crystal.