You may have heard of the Gemological Institute of America (GIA) before, as this is the most famous of all of the gemological grading laboratories. Nevertheless, there are a number of other labs that are trusted, including the Hoge Raad voor Diamant (HRD), the American Gemological Society (AGS), the two versions of the European Gemological Laboratory, i.e. EGL USA and ELG International, and the International Gemological Institute (IGI). Read on to discover the differences between the gemological grading labs.
The first thing to be aware of is that some laboratories are stricter than others, as they all differ in terms of how a diamond is graded. The reason why the Gemological Institute of America (GIA) is so well known and used is because it is believed to boast the strictest standards. However, the American Gemological Society (AGS) has not long been developed, and many are stating that they are just as strict. What makes the AGS different is the fact that they also have an ideal 'cut' grade - an extra one compared to the GIA. After these two labs, the Hoge Raad voor Diamant (HRD) comes next; it's almost as strict. The others are noticeably more lenient.
If you contrast certificates from the different labs, you will see what makes each one unique. They use different grading systems, their layouts are different, they don't use the same terminology, and some use diagrams whereas others do not. Nevertheless, when it comes to the actual quality of the diamond and the way it is graded, there are two aspects that need to be looked at closely - the colour of the diamond and its clarity. Let's take a look...
Colour - The GIA leads the way when it comes to strictness, and then we have HRD and AGS. EGL USA and IGI both rank colour by at least one grade higher, sometimes two. For instance, a diamond that is ranked 'D' by EGL, will only be ranked 'E' by IGI and EGL USA, and only 'F' by HRD, AGS, and GIA.
Clarity - When it comes to clarity, it is vital to recognise that 'Loupe Clean' is an extra grade that has been established by HRD. This is used to describe a diamond that has impurities that are not visible. Again, EGL USA and IGI rank clarity a grade higher or two. So, EGL INT. would grade a diamond FL, whereas EGL USA would grade it IF, IGI would rank the same diamond either IF- or VVS1, this diamond would likely be ranked LC- or VVS1 by HRD, and also VVS1 by AGS and GIA.