Good diamonds depreciate less than say cars or stereo equipment or computers. A Tiffany's ring with GIA certs can resell for half its original purchase price. There is an active secondary market in diamonds, so if you buy a high-quality GIA certified stone used, you should be able to sell it for a similar price to what you bought it for. Most of the depreciation on a diamond happens the moment you "drive it off the lot" so a used diamond is going to retain its value much better than a used car.

The key though is having a good quality stone from a reputable cutter with full certification. Diamonds are not fungible like say gold. A low-quality diamond purchased in an expensive mass-market ring isn't going to be worth anything on resale.

I used to share in that sentiment, but then I realized a wedding isn't about me, it is about showing the people who have been there for me over the years a great time. Marriage just becomes an excuse to bring them together. What is a few bucks to show someone close to you a fantastic night at least once in your life?

My wedding was stockily expensive by my standards (low to mid five figures), but with gifts we essentially broke even and the party was priceless. I would do it again.