One of the questions that always comes up around engagement season is the best way to handle the engagement ring if you're planning on proposing but want her to be able to pick it out. There are lots of stores that will give you a "loaner" ring, which you can then exchange when she's back by your side, but for a creative option that she can still wear for the rest of her life (and that's very inexpensive), these ring pendants from Polli might be just the ticket.
Offered in stainless steel and gold versions made from brass, they're quite dainty (you can see a model wearing one here) and have that slightly quirky Australian vibe that is cool while not being over-the-top. They also offer a huge range of other designs, everything from Brooklyn brownstones to trees to Matryoshka dolls that would make a great bridesmaid gifts; you'd get a unified look while honoring each bridesmaid personally.
I should mention as well that Polli was awarded a low CO2 rating for their Green practices. They use recycled metals in their jewelry, donate money from each purchase to the World Wildlife Fund, and (my personal favorite) each day share a communal lunch made from local organic ingredients to promote a healthy, happy team.