I haven't read all the responses you have gotten, and I'm sure you have been given some great ideas for everything.
You know your girlfriend best and I honestly think a more none-traditional ring is the way to go. I love the ring you found on etsy. If she loves blue, have you thought of an aquamarine stone? It's the stone sailors used to take with them when they went to sea to protect them. Also, if she does massages you could consider a bezel set stone...not only does that setting protect the stone, but there are no prongs to scratch anyone or get caught on anything. I found this ring on etsy to just give you an idea : http://www.etsy.com/listing/89457536/aqu..._facet=handmade
As far as the proposal...I think you should just wait until you feel the time is right....I don't think there is one "perfect" time to do it, when you feel it's right...that's when to ask her.
Good luck! I hope you find just what you are looking for!