Opal Body Tone Chart Explained (N1–N9)

One of the key characteristics used to describe and value an opal is body tone.

Body tone refers to the underlying darkness or lightness of the opal when the play-of-colour is not considered. This natural base colour can influence how vivid the colours appear within the stone.

Understanding the body tone scale can make it much easier to compare different opals and choose a stone with confidence.

What Is Opal Body Tone?

Body tone describes the base colour of the opal itself, independent of the play-of-colour.

Some opals have a very dark base colour, while others are much lighter or milky in appearance.

Because darker backgrounds can make colours appear stronger and more vibrant, body tone is an important factor in how an opal looks when worn as jewellery.

The Opal Body Tone Scale (N1–N9)

Jewellers commonly describe body tone using a numerical scale from N1 to N9.

This scale ranges from very dark stones to very light stones.

N1 – Jet Black

N1 represents the darkest body tone.

These stones have an almost completely black base colour. When strong play-of-colour is combined with this dark background, the intensity of the colours can be greatly magnified.

N2 – Very Dark

N2 stones are slightly lighter than N1 but still appear very dark.

They are still classified as black opal and can show strong colour contrast.

N3 – Dark

N3 opals remain quite dark but may show slightly more grey or dark charcoal tones.

Many Lightning Ridge black opals fall within the N2–N3 range.

N4 – Dark Grey

N4 stones begin to show a slightly lighter base tone, often appearing dark grey rather than black.

Opals in this category may still be considered black opal depending on the colour contrast.

N5 – Medium Dark

N5 stones display a mid-tone grey background.

They can still display good colour but typically appear softer than darker stones.

N6 – Medium

N6 opals have a lighter but still grey base colour and can often fall into the crystal opal category.

Because the base tone is lighter, the colours may appear more delicate.

N7 – Light

N7 opals have an off white or creamy body tone.

These stones are classified as white opal.

N8 – Very Light

N8 stones appear quite light, with a milky or soft white background.

Colour flashes are still beautiful but are often softer compared with darker opals.

N9 – White

N9 represents the lightest body tone.

These stones are typically classic white opal with a pale background.

Why Body Tone Matters

Body tone affects how strongly the play-of-colour appears within the stone.

Darker backgrounds often provide stronger contrast, which can make colours appear brighter and more dramatic.

For this reason, black opals (N1–N4) are often the most valuable when they also display strong brightness.

However, lighter stones such as crystal or white opal can still be incredibly beautiful and are often preferred for their softer appearance.

Body Tone vs Brightness

Body tone and brightness are sometimes confused, but they measure different characteristics.

• Body tone describes the base colour of the opal.

• Brightness describes how vivid the play-of-colour appears.

A darker body tone can enhance colour contrast, but brightness ultimately determines how vivid the colours appear.

Choosing the Right Body Tone

There is no single “best” body tone when choosing an opal.

Some people are drawn to the dramatic contrast of black opal, while others prefer the soft and luminous appearance of crystal or white opal.

The most important factor is selecting a stone that you enjoy looking at and feel connected to.

Opal Jewellery by Jack the Jeweller

At Jack the Jeweller, each opal is chosen for its natural beauty and individuality.

Whether a stone has a deep black background or a light crystal appearance, the goal is always to create jewellery that highlights the unique character of the opal.