Color grading system for opals
 

 Spectrum

 Body Tone

X1: Extra Wide Intense
Strong radiance and exceptional color play in a wide spectral range. Splashes fill over 90% of the body. Rich, contrast pattern.

X1-RO: Red-Orange shift
Strong radiance, intense color play with a dominance of red, orange and yellow hues. Splashes fill over 90% of the body.
Rich, contrast pattern.

X1-GG: Green-Gold shift
Strong radiance, intense color play with a dominance of green and warm yellow hues. Splashes fill over 90% of the body. Rich, contrast pattern.

X1-GB: Green-Blue shift
Strong radiance, intense color play with a dominance of green, blue and violet hues. Splashes fill over 90% of the body. Rich,
contrast pattern.

X2: Wide Intense
Good radiance and wide color play with a single hue prevailed. Splashes fill over 70% of the body. Sharp, distinct pattern.

X3: Evident
Moderate radiance and reduced color play. Splashes fill over 50% of the body. Disproportional pattern.

G1: Vivid Grain
Strong radiance and color play. Splashes fill over 70% of the body. Sharp granular or pinpoint pattern.

G2: Dim Grain
Moderate radiance and reduced color play. Splashes fill over 50% of the body. Granular or dusty pattern.

PP: Poor
Poor radiance with scanty color play. Splashes fill less than 50% of the body. Poor, blurred pattern.

Black (N1-N4)

Dark (N5-N6)

Light (N7-N9)

Crystal (N7-N9)


Comments

Gemval color grade system for natural opals is based on two independent scales: Spectrum and Body Tone.

Spectrum scale describes intensity of color play, spectral range of splashes, pattern coverage and overall quality of the pattern. Body Tone scale refers to the darkness/lightness of a basis mineral.

Gemval valuation system is not applicable to boulder, matrix, doublet, triplet opals or Mexican fire opals.


Current prices for natural opals

Historical values and trends

Gemstone color grading system


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