Focus on the solitaire. The setting costs far less that the diamond itself and can be altered in the future if desired. It is also essential to have a sense of how different shapes and sizes will look on your partner's hands and what her personal style is as she will be wearing that diamond all the time and for the rest of her life possibly. Pick something that reflects her style.
If possible, get one of her girlfriends (who she wouldn't suspect) to take her to try on different rings as a fun girls thing to do and share with you what looked good on her and what she liked in terms of the diamond and the setting style.
Set a budget. Buying diamonds can be daunting. We all want the best for the ones we love but most of us cannot afford a 7 carat D color Flawless clarity solitaire diamond. Neither would we be comfortable walking around wearing one. Set a budget so you can get her something appropriate to your lifestyle together. Not too big so she feels the need to put it in the safe nor too small of-course as women love their solitaires almost as a matter of pride!
Don't be too concerned with the old saying that the engagement ring should be worth two to three months' salary as that number can be too high for some folk and too low for others.
If you like something that is slightly above or below your budget and is perfect, trust your gut. If you are sure it’s ideal, she will probably love it. If you're not certain, trust her close family and friends but limit your advisers to 1 or 2 trusted persons to prevent confusion.
Don't involve too many people in the process or try to please too many family members as this only causes confusion and stress.
Take the time to learn about diamonds so you can make the right trade-offs. Everyone has different preferences when it comes to buying diamonds. Some factors such as size are more visible (a 1 carat looks significantly smaller than a 2 carat) and other factors such as clarity are less visible to the naked eye (you cannot distinguish between a VVS and a VS clarity diamond without magnification). Review different options so you know and understand what you purchase.
Don't be impatient or rush through the process. If you were buying a car you'd probably take your time and do significant research, do the same for an engagement ring.
In addition to being a milestone symbolic of relationships, engagement rings are also an investment. Diamond prices are affected by more than the 4 Cs. Seek the help of experts to explain these to you so you can maximize value to you in your purchase. Also, do make sure you purchase insurance for your valuables.
Personalize your engagement ring with a message. Inscribing something sweet on the inside of the ring is sweet and doesn't cost an arm and a leg.
When picking the setting, again consider how small or big your partners hands are and whether she's like something more ornate or simple. Make sure the accent diamonds on the setting match the quality of the solitaire to maintain consistency in the ring.
Try to get her accurate ring size when shopping so it must be sized a maximum of 1 to 2 times later. Having rings sized again and again affects the strength and structure of the ring particularly if it is diamond encrusted.
Even if you are an expert online shopper, go into a reputed store to understand characteristics of diamonds and the laboratories which certify them. I have encountered many a customers who thought they were getting a great deal but got a hazy diamond with strong florescence buying online. Don't trust a website blindly and read the fine print. Even though some websites advertise GIA as their certificate of preference, the diamond details note other less stringent certificates such as IGI. If a diamond is significantly cheaper somewhere, ask why. If it’s too good to be true, you are probably missing something.