This being said, diamonds that ARE certified by a gemological laboratory still need to be judged with an educated eye to avoid misrepresentation. Here are 3 areas to keep in mind when looking at diamond certificates to avoid being misled:
1. What laboratory is the certification from?
There are many different laboratories that issue Diamond Grading Reports. The Gemological Institute of America (GIA) and the American Gem Society Lab (AGSL) are generally the most accurate reports. These organizations are the originators of the color, clarity, and cut scales that the entire industry uses and therefore grade to the highest standards. Other laboratories such as the European Gemological Laboratory (EGL) and International Gemological Institute (IGI) use the same nomenclature as the GIA but do not grade to the same standards. Therefore, diamonds given grades by the EGL and IGI will typically given lower grades if graded by the GIA. This confuses many shoppers who see two diamonds with similar weight/color/clarity that are significantly different prices because one is GIA and the other is EGL. In reality, the EGL graded diamond is much lower quality than stated, which explains the difference in price.
Most diamond grading reports (especially those for diamonds 1 carat or larger) will be accompanied by a plot of the inclusions in the diamond. Regardless of who issued the report, these plots ALWAYS look a lot worse than the inclusions in the actual diamond. Some websites list their diamonds with a PDF file of the grading report, and many shoppers will eliminate certain diamonds simply because the plot lends them to believe the diamond is more imperfect than it probably is. As a rule of thumb, plots do not do many diamonds justice and I would recommend that anyone looking for a diamond see the diamond in person if possible, because plots often do not tell the whole story.
The most important aspects to pay attention to on a diamond grading report are the 4 C's. Carat Weight, Color, Clarity and Cut. Cut grades often requires a little extra attention since different labs grade cut differently, but in general anything called "Excellent" or "Ideal" should be a nicely cut diamond. However, there is a fifth category called "finish" which details a diamonds polish (how perfectly each facet is polished) and symmetry (how perfectly the facets are arranged). These qualities of a diamond are usually invisible to the naked eye, and should NOT affect a purchase decision if they are do not meet excellent or ideal standards. A diamonds proportions (cut) are far more telling of a diamonds overall brilliance than it's finish.
Also, fluorescence gets a bad reputation in the diamond industry, mainly because it is not disclosed. Many diamonds (especially yellower diamonds) have blue fluorescence under UV light. From my experience, 99% of diamonds with faint to medium blue fluorescence do not look noticeably different in most lighting environments. Only diamonds with "Strong" or "Intense" blue fluorescence would ever have a noticeable blue tint in direct sunlight, so do not poo poo any diamond with some degree of fluorescence if everything else about the diamond meets your expectations.
I hope this helps anyone shopping for a diamond to keep their head in the right places. We currently have GIA and EGL graded diamonds listed on our website for anyone interested in seeing the comparison. Click the link below to visit our Diamond Search.