GIA is an acronym for the Gemological Institute of America which is an independent, nonprofit organisation, considered to be the world's most reputable and widely recognised diamond certification organisation and geological research institute. The GIA tests diamonds and grades them based on the 4 C's: carat weight, cut, colour, and clarity. GIA provides diamond grading reports that offer information about a diamond's quality and characteristics.
Therefore, the GIA certified lab grown diamonds are the top of the range for quality.