In fact, since no two diamonds are alike, inclusions can act as tiny birthmarks that help identify one diamond from another under magnification. Still, the clarity of a stone is a factor to consider when making your purchase decision. Both the GIA and AGS offer unique rankings in determining the clarity of a diamond. In the case of a diamond, it depends. Since the average size of a diamond engagement ring sold in the U.S. is 75 points, that means it weighs .75 carats.
Jewelers usually measure carat weights in carat increments.
Reputable jewelers often carry scales that can measure down to .002 of a carat, so ask your jeweler to show you how they determined the weight of the stone you're considering. As you can see, many factors go into the purchase decision of buying an engagement or wedding ring. Unless money is no object, you'll likely be considering all four factors and the trade-offs of size versus quality or quality versus size. You can select your preferences among the Four C's to get an idea of what you should expect to pay for different feature combinations. Luckily, these days, any reputable jeweler should provide you with a certificate stating the authenticity of the diamond, including its quality, weight, and the cut of the stone.