There are five laboratories that certify loose diamonds, inducing the two most popular – the European Gemological Laboratory (EGL) and the Gemological Institute of America (GIA). These two laboratories have different grading techniques.
* GIA certification. This is the world’s most popular certification, especially for diamonds under 1 carat. The mission of this nonprofit institute is to protect all gemstone buyers and sellers by maintaining standards to evaluate gemstone quality. This certification is considered the gold-standard for diamond evaluations.
* EGL certification. This U.S. certification is popular among consumers, although standards tend to be “looser” than those of the GIA. The EGL is also a for-profit organization.
When it comes to buying antique jewelry with a gemstone or diamond, make sure to look for GIA certification.