You can make or buy a card and pop your present on it...
such as a necklace threaded through holes on the front of the card (as seen in my example). you can also do this with earrings or a bracelet etc.
You can make a home made card to propose with, simply write the question and buy a mini wooden peg from a craft store (I got a pack of these cute little pegs with hearts on from hobbycraft). You can use the little peg to hold the engagement ring.
This is quite a nice idea as your partner will be very surprised as she will think it is just a card for valentines.
Alternatively, you can use a piece of ribbon to hold the ring, or even tie/peg it on the inside of a normal valentines card as an extra element of surprise.
This is another idea of how you could propose, although you could write "happy valentines day" instead if you aren't ready to propose yet but would like an unusual gift presentation. I simply used a card butterfly and empty box with a little bit of blue-tac to hold this ring and wrote "marry me?" across it's wings.
If your not quite ready for that step, you can always just ice a nice message on the chocolates instead :)
here you can see a simple example, but you can ice whatever you like.
...or you could always just buy a pretty piece of jewellery (use the "contact" page of the website to see what is currently in stock, or to discuss a commission).
HAPPY VALENTINES DAY!