Lapis Lazuli Gemstones – Properties, Origins, Treatments and Buying Guide

Lapis Lazuli is one of the most historic and striking gemstones, prized for its intense deep blue colour and gold pyrite flecks. Unlike brightly coloured stones that rely on heavy saturation, lapis lazuli is valued for its natural combination of ultramarine blue, pyrite inclusions, and sometimes calcite veining.

In this guide we examine lapis lazuli from a professional gemmological and commercial perspective, covering its physical properties, crystal structure, treatments, origins and how to identify fine-quality stones.

Lapis Lazuli is a rock composed primarily of the mineral lazurite, with minor amounts of calcite, sodalite, and pyrite. It has been mined and used for thousands of years in jewellery, carvings, and pigment production. Unlike crystalline gemstones, it is a metamorphic rock, so its colour and patterning can vary naturally. High-quality lapis lazuli has an intense deep blue with minimal calcite and evenly distributed pyrite specks.

Lapis Lazuli is primarily composed of:

Lazurite (25–40%, gives deep blue colour)
Calcite (white veining)
Pyrite (gold flecks)
Minor sodalite, diopside, and other silicates

The proportion of lazurite determines the intensity of the blue, while pyrite adds the characteristic sparkling effect. High-quality lapis lazuli has minimal calcite and evenly distributed pyrite.

Lapis Lazuli belongs to the tectosilicate mineral family because of its major component lazurite.

Its crystal system is isometric (cubic) for the lazurite mineral, but as a rock, lapis lazuli does not form uniform crystals. The rock is typically massive, compact, and suitable for carving and faceting.

Lapis Lazuli combines deep blue colour, golden pyrite inclusions, and occasional white calcite streaks to produce a unique and ornamental appearance.

Lustre
Vitreous to waxy; polished stones exhibit a smooth sheen.

Transparency
Opaque to semi-translucent in thin sections; fine jewellery pieces may show slight translucency at edges.

Refractive index
1.50 – 1.60, variable depending on mineral composition.

Specific gravity
2.7 – 2.9, depending on lazurite and calcite content.

Lapis Lazuli is prized for its rich blue colour, often with:

Deep ultramarine
Gold pyrite flecks
Occasional white calcite streaks

The most valued stones have intense, uniform blue with minimal calcite and evenly distributed pyrite.

Lapis Lazuli has a Mohs hardness of 5 – 5.5, making it moderately soft.

It is suitable for pendants, earrings, beads, and decorative carvings but requires protection from sharp knocks in rings.

Most lapis lazuli is untreated. Occasionally, low-grade stones may be dyed to enhance blue colour or impregnated with wax/resin to improve polish and durability. High-quality material is natural with no enhancement.

Avoid ultrasonic and steam cleaners.
Do not expose to acids or harsh chemicals.
Clean with warm water, mild soap, and a soft cloth.
Store lapis lazuli separately from harder gemstones.

Major sources of lapis lazuli include:

Afghanistan (Badakhshan)
Chile
Russia
Pakistan
United States (California, Colorado)