COLOUR INTENSITY SCALE

Only the faintest trace of colour, often appearing pastel or near-colourless, with a soft and delicate look.

Soft, pastel hues with low saturation and tone; colours appear delicate and almost washed out.

Noticeable but gentle colour, brighter than pale, yet still soft and airy in appearance.

Clear and lively colour that is stronger than light but not yet intense; retains brightness and openness.

Displays balanced saturation with rich colour tones that remain bright and lively without appearing dark.

Maximum saturation without heaviness; colours appear bright, pure, and strikingly intense.

Strong and dark in tone, producing rich, dramatic hues though with reduced brightness.

Very strong tone where colour appears heavy or inky, vibrancy is reduced and brilliance often masked.

Note: Industry trade names such as “pigeon blood” ruby or “cornflower blue” sapphire fall within these categories, but are not shown separately here. A stone-specific guide to help place these follows below.

LUSTRE/BRILLIANCE SCALE

Exceptional shine and bright reflections, showing strong light return and a crisp sparkle.

Noticeable brightness but with softer reflections and a more subtle overall glow.

Soft and muted appearance, often near-opaque looking with minimal internal light.

CLARITY SCALE

No visible inclusions to the naked eye.

Minor inclusions can be seen without magnification but don’t significantly affect beauty.

Obvious inclusions visible to the eye, often affecting brilliance.

CUT QUALITY SCALE

Precise and symmetrical with well-defined facets and a clean, polished finish.

Generally well-cut with fair symmetry and proportions, may show soft facet definition.

Irregular or uneven cut with softened edges or visible imperfections.