As soon as you start looking at diamonds, and after you have carefully seen a few. You will start noticing that a very important aspect is how the stone was cut. There are experts hands that can masterfully cut a diamond to sparkle even more. You will notice and detect which is better after a while. Trust your instincts.
The typical engagement ring stone is one carat. It will
suit your bride perfectly and most surely will make her very happy.
Again as in cut, clarity is also important, some stones are clearer than others, they might have impurities or be completely clear. Look carefully, learn and decide.
Diamonds can have many tones. You or your spouse might have a special color in mind. It is perfectly normal for diamonds to have shades.