Opal Body Tone Scale

We can evaluate opal body tone using the standardised Munsell colour system

November, 2017

The Munsell Colour System is a colour space that is comprised of three colour dimensions – value (light to dark), hue (colour) and chroma (colour intensity). For opal body tones, we will be referring to the ‘value’ dimension and this divided into nine shades from black to white.

Opal body tone colour scale:

  • Nine shades ranging from black (N1) to white (N9)
  • N1 – N4 is considered black base tone, or black opal
  • N5 – N6 is considered semi-black base tone
  • N7 – N9 is considered light base tone, or white opal


Exhibit 1 – Opal body tone scale

Opal Body Tone Scale
Opal Body Tone Scale – Black opals (N1) to White opals (N9)

Source: Developed by Geological Society of America using the Munsell Colour System

To view our selection of opals then click on this link.