But before you propose, you'll have to make some decisions. Follow our guide to make sure you've got all your bases covered.What does she like?
Finding out what she likes shouldn't be too hard. If she hasn't already spoken to you about it, she's surely to have mentioned it to her closest friends. Otherwise, you can always ask her mother - you're sure to score some points by letting your future mother-in-law in on the big surprise first. If all else fails, just take a look at the rest of her jewelry and you should at least be able to tell if she prefers yellow gold or white gold and start from there.
Choose a quality jeweler
In making such an important purchase, it's important that you choose the right jeweler who will help you find exactly what you want and deliver it on time.
Set your budget
When setting your budget, keep in mind that you are purchasing both a setting and a center stone. The familiar standard of spending two months' salary on an engagement ring is a good starting point. Before you settle on a specific amount to spend, take some time to learn what qualities you're looking for in both a diamond and a setting. Regardless of what style engagement ring you choose, it should be of the best possible quality available in your price range.
Choosing the right diamond
Like any important purchase, you should understand what you're buying before choosing a diamond. Start by choosing a diamond shape that best fits her style. Learning about the Four Cs (cut , color , clarity and carat weight) and certification will help you determine which qualities are most important to you and her. Last but not least, you'll have to settle on a size for your diamond. Bigger is not always better, especially when it comes to diamonds. Only once you know what qualities are important to you will you be able to narrow down your search for that perfect diamond.
Choose a setting and a band
There's more to the diamond when you're purchasing a diamond ring, of course. There's the setting (also called the mounting). This, like the shape of the stone itself is purely a matter of personal style. In addition to the style, the metal that the setting itself is crafted from is an important consideration.
Information by : http://www.diamond.com