Congratulations
At the risk of sounding like a curmudgeon I would ask you to reconsider the diamond purchase if you wife is a liberal creative person she might go for it. Still a ring of course but why a diamond? The diamond engagement ring was largely a
creation of a monopoly DeBeers to sell more diamonds, it is an artificially, commercially driven tradition.
I really like jewelry and this Christmas I bought my wife a beautiful Topaz ring and a nice pair of emerald earrings. I find other gemstones far more interesting than diamonds. I do not think a diamond solitaire ring is very attractive unless the stone is quite large and of good quality but then you are talking some very serious money. But even with serious money a decent sapphire, ruby or emerald to me is a far more interesting gem, note that good quality sapphires, rubies, and emeralds are more expensive than diamonds on a per carat basis. Plus everyone knows diamonds then they are always sizing upthe gem and figuring how much it cost you much better to add some mystery to the whole thing.
If your bride to be has blue eyes consider getting a blue sapphire to match. If you are on a tight budget you can even consider getting an "artificial" or laboratory created sapphire. Here you can get a really large stone that is perfect (too perfect?) is genuine sapphire and in a setting with some genuine diamonds along side can really look stunning. If anyone asks yes it is real ruby or emerald or sapphire.