We need to get an engagement ring and a wedding ring.  We'd like diamond and white gold/platinum colour for the metal.  A friend of mine who used to work retail in a jeweler said buying new is a waste of money because its cheaper to pick up 2nd hand rings on trademe or at auctions.  Someone else said get the diamonds yourself and have a ring made, apparently that's cheaper too.

Has anyone got advice around good ways to get rings (for a woman) that will help us keep our budget down?  If the advice is to go new we'll just have to suck it up, but there's a few house items on our want list and we'd have to compromise on getting them if we splash out on the rings.

We saw some we liked at auction but it was too small, are rings easily resized?

Overseas options?

Lab made diamonds? (I looked at a few and saw little price difference, but it was a really fancy shop).

Any info you think is helpful will be welcomed.