Usually when you buy diamonds online, they are loose diamonds or diamonds engagement rings, these stones have been graded, tested and examined by a gemologist. This is what a certification is for. If your diamonds come with a certification, you can know for a fact that they are in fact real diamonds, but also that they are quality diamonds. The certification of a diamond is also known as Diamond Grading and is an overall report of where the diamond is from, who graded it, and what grade it received. It also includes the exact measurements, weight, and cut of the diamond.
Each stone is going to be unique, so it's important that each one be graduated to ensure quality. For loose diamonds especially, it's absolutely essential that your package comes with a certification. Will you receive this certification before or after you buy diamonds online? Well, loosely speaking you should receive the report before you buy it. This is to guarantee you the consumer that your product is what the seller claimed it to be. Some of the jewelers and jewelry stores out there that sell diamonds engagement rings, white gold diamond engagement rings, or loose diamonds will label the stones as being Ideal, Excellent, Belgium Cut or Fine Make. If you see these terms being used, be sure to confirm that the diamonds are indeed what the seller is categorizing them to be.
When it comes to the grading report, there are specific laboratories that you want to make sure the report has been accounted for by. Look for well known labs including the Gemological Institute of America (GIA), the Diamond Certification Laboratory of Australia (DCLA), the American Gemological Society (AGS), or the Hoge Raad Voor Diamant (HRD), European Gemological Institute (EGL) or the International Gemological Institute (IGI). These are all official diamond grading labs which reports you can trust. If your report contains a lab other than those above, chance are you looking at a fake or poor-quality diamond.
Each one of these labs is going to obviously have its own grading system, but for the most part they still all go by the same criteria. This criterion is of the highest degree. Sometimes, however, when you buy jewelry from a jewelry store online, you might not receive a report, in which case case it is your responsibility to ask for one. If the sellers give you a hard time or they can not produce one, it looks like it's time to go someplace else to buy diamonds.
If certification, grading and quality means nothing to you, then you will not have to worry about this. But, I can guarantee that if your fiance finds out you bought her one of those less than amazing diamonds engagement rings or white gold diamond engagement rings, she is not going to be a happy camper, and neither will you! Spend the money, get a great diamond that you can keep for years to come, and be confident in knowing you made the right choice.