Colour

One of the fundamental 4Cs: the less colour a diamond has, the greater its value. The GIA scale runs from D (perfectly colourless) to Z (heavily tinted yellow).

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Clarity

Measures the presence of internal inclusions or surface blemishes. The purer the diamond, the more light passes through it and the higher its value.

IF — Internally flawless, no inclusions

VVS1 / VVS2 — Minute inclusions, very difficult to see even under high magnification

VS1 / VS2 — Minor inclusions, difficult to see under 10x loupe, invisible to naked eye

SI1 — Inclusions detectable under 10x by expert, invisible to naked eye

SI2 — Inclusions sometimes visible to naked eye; we recommend case-by-case evaluation

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Cut

Describes how the proportions of a diamond affect its brilliance and light return. It is the most important of the 4Cs. Excellent and Very Good are the best values; Good is acceptable.

Excellent — Ideal proportions: maximum brilliance and light return.

Very Good — Proportions very close to ideal, very high brilliance.

Good — Acceptable proportions, slightly lower brilliance.

Symmetry

Evaluates how precisely the facets align and intersect. Minor asymmetries can affect light travel and brilliance. Excellent and Very Good are recommended.

Polish

Describes the quality of finish on the outer surface of the diamond. A high grade maximises light reflection and brilliance.

Fluorescence

About one third of natural diamonds emit a completely harmless bluish glow under UV light. Fluorescence rarely affects appearance; in very rare cases it may cause a slight milky effect.