Diamonds are graded mainly for color and clarity. The first scale for color goes from "D" color which is the highest and the most expensive indicates that there is no tint in the stone weather yellow or brown or any other color. Jewelers call the "D" color colorless. Then we go down to E, F, G, H, I...Z. The difference between each shades are very thin and will be very difficult to an untrained eye to tell the difference between one shade to the other. It is very common to hear diamond dealers arguing between themselves on a color of a diamond.

It is easier to determine clarity grades but still a thin line separates them. There are different degrees of clarity in diamond grading. No flaws to a 10X loupe by an experienced grader is flawless and as the inclusions get larger and positioned near the center the grade goes down: FL, IF, VVS1, VVS2, VS1, VS2, SI1, SI2, SI3, I1, I2, 13. The lower grades just came into existence in the last 10 years or so (SI3, I3) since folks have been buying lower quality stones. FL=Flawless, IF=Internally Flawless, VVS=Very Very Slightly Included, VS=Very Slightly Included, SI= Slightly Included, I=Inclusions Visible To The Naked Eye.

If you want to educate yourself more in the subject, make a quick search on the internet, there are a lot of sites that will explain more into depth.

Last advise, buy a diamond that is certified by a known diamond laboratory like "GIA" "EGL" or "AGS"
Once you buy a certified diamond, it indicates the color and clarity by a lab that is a third party and is independent.

Get your local jeweler to take a look at your diamond. They have a diamond probe which sends heat pulses into the gem to tell if it is real or not. Most jewelers will do this for you at no charge because it's a 'Good Will' thing. You may be a future client of theirs. If they won't do it - find another one who will. Once you have that knowledge, you can then decide if you want a full appraisal or not. They will charge for this but it will be worth it, simply to solve the puzzle. For the cost of one night out - you will have the answers for a lifetime.

Where does the light come from that makes a diamond sparkle? The light comes in from the top and is refracted and reflected in the diamond causing dispersion which is breaking up of the white light into spectral color. This can only be achieved if the diamond is cut perfectly.

The brilliant is the white light that is reflected from the top of the stone the table, and the sparkle is called scintillation which is the small flashes of white light off the crown facets. Star 129 diamonds is a new brand of diamond that has done an amazing job of improving the old standard of 58 facets by adding so much more on the bottom.