I am proposing to my darling in about a week - and I just bought a beautiful gold & sapphire engagement ring using Bitcoins.
Yes - I paid for it entirely and directly in Bitcoins!
It was bought from David Fortier of Tip Top Gem in Thailand. (He sells loose stones on bitmit but also does custom jewelry)
I highly recommend David's work. He was extremely helpful and knowledgeable and sourced some stunning stones for me before having them set into an 18K white gold ring.
I suspect there have been other engagement rings bought with Bitcoins by now - I remember this thread from Roger Ver, where he was attempting to buy a diamond engagement ring with Bitcoins - but I don't know what the outcome was:
I only paid a bit less than 20 BTC - I'm not a Bitcoin mogul like Roger Ver!
At the time(s) of payment those Bitcoins were at a few different rates above $100USD/BTC - as I paid David as he sourced the stones and then again later for the final ring work.
The whole process really brought home to me how convenient Bitcoin is as a payment mechanism for projects.
The merchant can get fast payment so they're not out of pocket whilst sourcing materials.
I had the ring independently valued here in the Sydney CBD by a registered member of the National Council of Jewellery Valuers (Anania Jewellers) and they confirmed that the sapphires were genuine and as described and the gold tested as 18K. They gave me a replacement value a fair bit higher than what I paid - so I believe David gives very good value for gems and jewellery.
My darling hasn't yet seen the ring - but once I've given it to her, I may post a photo here.
Edit: ok, I think my girlfriend is pretty unlikely to come into these forums unaccompanied by me.. so I'll put up the photos.
I'm no photographer - but I think these capture some of its beauty.
The 2 side stones are white sapphires. I like the idea of it being an all-sapphire ring.