Diamonds are graded in four ways: usually called the 4 Cs: color, carat weight, cut and clarity. The most important aspects are: color and clarity: .
Clarity ranges ru…ns from Flawless and Internally Flawless, and includes VVS (very, very slight imprefections) to I which means that the diamonds is included with visible spots or cuts -- whatevers, that change how it appears. Included diamonds are the least expensive diamonds sold as jewelery. .
Color begins at D and runs through Z. D means very white, F means very good, G-H means good color, and I- Z indicates that there is more yellow visible to the naked eye the further down the alphabet the grade is applied. Some cheaper jewelry made by the millions uses clarity I and less white diamonds because they cost less as raw materials. .
Carat weight speaks for itself: it's the weight of the stone. .
Cut can be princess, round, trillion, and so forth. So, for example, if a diamond is clarity VVS, color: D, it is an excellent, probably a more expensive diamond. A good range is E-H, clarity: VVS - SI. .
The more flawed a stone, the less expensive it will be .
The closer the letters get to I and further down the alphabet indicate that the diamond is a lot less desirable, and probably should be a lot cheaper. Your jeweler can tell you more, and you can look up all the information you need to learn about diamonds. Research before you buy, because not every jeweler is honest, although a good jeweler should be. You can ask for a certified gemological certificate for the stone you are buying, so that you know the unique physical properties of your investment. This is different from a jeweler's appraisal. ( Full Answer )