GIA Diamond Grading Standards
GIA diamonds are examined by a minimum of four highly trained diamond graders and gemologists. At each step of a diamond's evaluation, a more senior staff member independently grades the stone. To ensure impartial evaluations, the distribution of diamonds to graders is a completely random process.
- Diamond Carat
- After a diamond's carat weight is determined, its measurements, depth, table, angles, culet, and girdle thickness are recorded.
- Diamond Color
- A diamond's color is graded on a scale ranging from D (colorless) to Z (light yellow) by comparing it to master stones of predetermined color.
- Diamond Clarity
- Clarity is assessed on a scale ranging from FL (flawless) to I3 (included) based on an examination of the stone under a binocular microscope of 10x magnification. The stone's characteristics are plotted on a diamond diagram.
- Diamond Cut Grade
- Cut grade is established for brilliant round-cut diamonds based on the analysis of the stone's craftsmanship and light interaction. The level of a diamond's craftsmanship is determined by evaluating its polish, symmetry, and proportions. The stone's light interaction is based on its brightness, scintillation, and fire. The GIA designates the quality of a cut on a grading scale ranging from Excellent to Poor.
- Polish & Symmetry
- A diamond is evaluated for polish and symmetry on a grading scale ranging from Excellent to Poor. The grade is based on an inspection of the diamond's craftsmanship.
- Diamond Fluorescence
- A diamond's fluorescence is determined as None, Faint, Medium, or Strong based on its reaction to ultraviolet light.
- Laser Inscription
- For added security and identification, a diamond's girdle can be laser inscribed with its GIA report number. The GIA offers laser inscription services for all of the loose diamonds they grade.