Prasiolite Gemstones – Properties, Origins, Treatments and Buying Guide

Prasiolite, also known as green amethyst, is a refined and elegant member of the quartz family, prized for its soft to vivid green hues. Unlike stones with intense saturation, prasiolite owes its charm to its subtle transparency, gentle colour, and natural brilliance.

In this guide we examine prasiolite from a professional gemmological and commercial perspective, covering its physical properties, crystal system, treatments, origins and how to identify high-quality stones.

Prasiolite is the green variety of quartz (SiO₂), commonly formed by heat-treating amethyst or rarely occurring naturally in pale green crystals. Its gentle green colour ranges from soft pastel to a slightly deeper olive green.

Prasiolite crystals grow in hexagonal quartz prisms, producing transparent and facetable gemstones suitable for fine jewellery.

Prasiolite has the chemical formula:

SiO₂

It is composed primarily of:

Silicon
Oxygen

Trace elements (iron) may influence the green colour. The colour of natural or heat-treated prasiolite is generally pale to medium green, with minimal inclusions for high-quality stones.

Prasiolite belongs to the quartz (silicate) mineral family.

Its crystal system is hexagonal, forming elongated six-sided prisms with excellent transparency and optical clarity.

Prasiolite offers a combination of gentle green colour, brilliance, and clarity that is ideal for pendants, earrings, and collector’s pieces.

Lustre
Vitreous, providing a clear glass-like sparkle.

Transparency
Transparent to translucent, with high clarity in gem-quality stones.

Refractive index
1.544 – 1.553, offering gentle brilliance and sparkle.

Specific gravity
2.65, typical of quartz gemstones.

Prasiolite occurs in shades of:

Pale green
Soft olive
Yellowish-green

The most valuable stones are evenly coloured with minimal brown or yellow tint.

Prasiolite has a Mohs hardness of 7, making it suitable for rings, pendants, and earrings with proper protective settings. It has good toughness but can chip if struck sharply along inclusions.

Most prasiolite is produced by gentle heat treatment of amethyst to achieve its green colour. Natural green prasiolite is rare. High-quality stones are untreated aside from heat enhancement and free from coatings or fillings.

Avoid harsh chemicals and sudden temperature changes.
Use warm water, mild soap, and a soft brush.
Store prasiolite separately from harder stones to prevent scratching.

Major sources of prasiolite include:

Brazil
Poland
Canada
USA (Arizona)
Namibia