Brilliance is the other term associated with the excellency of the cut of a diamond. The "Cut" is what unleashes the “Light” within a stone and gives its ability to “dance”. The "cut" refers to the brilliance of the stone, determined by the quality and proportion of its facets. The interaction of the facets with the light is what gives the diamonds their unique sparkle and brilliance.
Polish refers to the quality and smoothness of each facet of the stone. Facets are the flat, polished surfaces on any side of the gem. Tiny defects, invisible to the naked human eye, can disrupt the light patterns as the light rays enter and exit the gemstone. Polish quality is measured based on the severity of those surface imperfections.
Symmetry is the precision of the alignment and intersection of the facets of the gem. It is what makes the “light” travel properly through the stone. Symmetry is judged based on the ideal proportions between all the facets of the gem, specific for each shape. Symmetry often has a serious impact on price.
The GIA Diamond Grading Report includes an assessment of a diamond’s 4Cs – color, clarity, cut, and carat weight – along with a plotted diagram of its clarity characteristics and a graphic representation of the diamond’s proportions. For standard round brilliant cut diamonds falling in the D-to-Z color range, the report also includes a GIA Cut grade.
The GIA laboratory issues diamond grading reports for loose, natural diamonds in the D-to-Z color range that weigh 0.15 carats or more. GIA Diamond Grading Reports are not issued for diamond synthetics, diamond simulants, mounted diamonds or those that have undergone unstable treatments, such as fracture filling or coating. And while reports may be issued for diamonds that have been laser drilled or HPHT processed, reports will indicate that the diamond has been treated.
The GIA Diamond Dossier offers the same grading information as the GIA Diamond Grading Report but without the plotted diagram. As an added security feature, the Dossier service includes a microscopic laser inscription of the report number on the diamond’s girdle.
The GIA laboratory issues the Diamond Dossier for loose, natural diamonds between 0.15 and 1.99 carats, in the D-to-Z color range. The Diamond Dossier is not issued for synthetics, simulants, mounted diamonds, diamonds that have undergone unstable treatments such as fracture filling or coating, or those that have been HPHT processed. Any evidence of other treatment is disclosed in the report.
Also available are the GIA Diamond eReport and the GIA Diamond Focus Report™, online only reports including full 4Cs grading results.