Where to buy natural engagement ring?

I'm looking to buy one for the lady in the next year or 2. We've decided it's going to be natural and I'm looking for a jeweler that offers reasonable pricing and good aftercare + warranty. For example, my friends in Seattle bought from Shane Co and all their rings come with lifetime warranty plus if you trade the ring back in, they will take it back at MSRP (in store credit) and you can add cash on top to upgrade if you'd like.

What are your recommendations? TIA!