When you finally purchase a diamond many times it will come with what your Jeweler may call a Diamond Certificate. This term in itself is a bit misleading. The word “certificate” gives one the misconception that the grade on their diamond has been certified or guaranteed. Nowhere on this mysterious piece of laminated paper is the word certificate so why do they keep using it? These are called Diamond Reports. It says so right on the front in big letters. The truth of the matter is that the first 5 words on the report’s disclaimer are “This report is not a guarantee”.
It could be said that Gemology is a science of educated guesses. Much of the criteria used in grading a diamond cannot be measured or weighed but rather needs to be estimated by combining data, opinion and experience. This being stated, I still suggest you insist the diamond you purchase comes with a report from an accredited Gem Lab that is located in the United States.
The Gemological Institute of America (GIA) is by far the most reliable Gem Lab in the world. They developed the grading scale that is used today to grade diamonds and they are responsible for the training and accrediting some of the finest Gemologist in the world. Below is a copy of one of their reports.

The reports are fairly straight forward in their format. Their job is to give you a detailed list of data to help you in the evaluation and identification of your diamond. Below is a brief breakdown of each category.
GIA Report Number • This is the number the GIA uses to identify your report and diamond. Many times the report number will be laser inscribed on the your diamond as the image below shows.

Shape and Cutting Style • This tells you what shape your diamond is. The most popular shapes are the Round Brilliant, Princess Cut, Radiant Cut and Cushion Cut Diamond. We have a page with many of the shapes diamonds have been cut in over the years at our website at www.gregorydiamond.com/shapes
Measurements • On a Round Brilliant they measure the circumference and the depth of the diamond. On Fancy Shapes they measure the length, width and depth of the diamond.
Carat Weight • Carats refer to a diamond’s weight. The term carat comes from the carob bean which was once used to weigh gemstones because carob beans have a uniform weight. One carat equals 200 mg while 5 carats are equal to one gram.
Color Grade • The color scale runs from D (colorless) to Z (fancy Yellow) think of this as having a small glass of water and introducing yellow food coloring to the glass one drop at a time . With each drop the water in the glass takes on a warmer color and hue. This is how the color grading scale works.

Clarity Grade • When a diamond forms in the earth it is not under perfect conditions. Many impurities are present and they become become part of the diamond. The less foreign material in the stone the rarer and more valuable it is. This is why a one carat diamond can run anywhere from $600.00 to $19,000.00.

Cut Grade • The cut grade category is fairy new on most Diamond Reports. For many years Gemologists have been trying to develop a system for classifying the overall beauty of a diamond. This has been no easy task due to the subjective nature of Gemology. With all the variations of proportion, angles and finish that play into a diamonds beauty it is a difficult job trying to classify what combination yields the most brilliant diamond. You can click here to read an article from the GIA’s website with a more indepth explaination of the tolerances for the GIA diamond cut grading system that is promised to make your head hurt.
Finish • The finish of a diamond is broken down into 2 categories. Polish and Symmetry.
Polish • Polish refers to the quality of the polishing of each individual facet. Is it free from irregularities and grain lines.
Symmetry • Symmetry is how all the individual facets line up to each other. Do the lines flow straight from facet to facet or are there irregularities that cause the lines to miss their intersections.
Fluorescence • Fluorescence is a common phenomenon in diamond. When examined under invisible ultraviolet rays many diamonds will to glow blue, green, yellow, orange, or a combination of these colors. On a diamond report you will see fluorescence identified by its color and also by its strenth (none, faint, medium, strong, and very strong). The most common color for fluorescence in a diamond is blue which in medium and lower strenths many times will make lower color diamonds look better than without it. Most of the time fluorescence will not have a visual impact on a colorless or near colorless diamond unless it is strong to very strong which can cause a diamond to look milky.