Diamond Equivalent Colour Grade (ECG)
The Diamond Equivalent Colour Grade (ECG) is a system used to compare the colour grades of diamonds assessed by different grading laboratories. It provides a reference for understanding how diamonds graded by one lab compare to those graded by another, ensuring consistency in colour evaluation.
Why is ECG Important?
Different diamond grading labs may have slight variations in colour grading.
ECG helps align grading standards, making it easier for buyers, jewelers, and investors to compare diamonds accurately.
It is particularly useful when dealing with non-GIA or non-DCLA graded diamonds.
Comparison of Diamond Colour Grades Across Laboratories
GIA Grade DCLA (CIBJO Standard) HRD Grade IGI Grade AGS Grade EGL Grade
D (Colourless) D D D 0 000
E (Colourless) E E E 0.5 000
F (Colourless) F F F 1 000
G (Near Colourless) G G G 1.5 000
H (Near Colourless) H H H 2 000
I (Near Colourless) I I I 2.5 00
J (Near Colourless) J J J 3 00
K (Faint Yellow) K K K 3.5 00
L (Faint Yellow) L L L 4 0
M (Faint Yellow) M M M 4.5 0
N-R (Very Light Yellow) N-R N-R N-R 5-7 0
S-Z (Light Yellow) S-Z S-Z S-Z 7.5-10 0
GIA (Gemological Institute of America) is considered the strictest in grading.
DCLA (Diamond Certification Laboratory of Australia) follows CIBJO standards, aligning closely with GIA.
IGI, HRD, and EGL may have slightly looser grading standards.
AGS (American Gem Society) uses a 0-10 numerical scale where 0 = D (colourless) and 10 = Z (light yellow).