Spinel Gemstones – Properties, Origins, Treatments and Buying Guide

Spinel is one of the most vibrant and durable gemstones, celebrated for its red, pink, purple, and blue colours. Unlike stones enhanced by coatings or inclusions, spinel achieves its brilliance naturally, with high clarity and excellent refractive properties.

In this guide we examine spinel from a professional gemmological and commercial perspective, covering its physical properties, crystal structure, treatments, origins, and tips for identifying fine-quality stones.

Spinel is a magnesium aluminium oxide mineral (MgAl₂O₄) belonging to the spinel group of minerals. It occurs in metamorphic rocks and alluvial deposits. Its natural brilliance, hardness, and vivid colour make it a preferred choice for rings, pendants, earrings, and collector specimens.

Spinel has the chemical formula:

MgAl₂O₄

Primary composition:
Magnesium
Aluminium
Oxygen

Trace elements such as chromium, iron, or zinc can modify colour, producing red, pink, purple, or blue stones.
The most prized spinels display vivid, pure colours with excellent transparency.

Spinel belongs to the spinel group of minerals.
Its crystal system is isometric (cubic), often forming well-defined octahedral or cuboid crystals. This symmetry contributes to its brilliance and faceting potential in jewellery.

Spinel combines vibrant colour, excellent clarity, and strong refractive brilliance, making it a standout gemstone in jewellery and collection specimens.

Lustre
Vitreous, giving a lively sparkle.

Transparency
Transparent to very slightly included; gem-quality spinel is highly transparent.

Refractive index
1.712 – 1.736, giving strong brilliance and sparkle.

Specific gravity
3.58 – 3.61, typical of spinel gemstones.

Spinel occurs in a wide variety of colours:

Red
Pink
Purple
Blue
Black
Orange

The finest spinels display pure, vivid colours with minimal zoning.

Spinel has a Mohs hardness of 8, making it durable and suitable for daily wear in rings, pendants, and earrings.
It has good toughness and resists chipping better than most gemstones of similar size.

Most <a href=”https://www.igemz.co.za/product-category/natural-gemstones/spinel/” target=”_blank”>spinel</a> is untreated. Occasionally, minor heat treatment may be applied to improve colour. High-quality stones have no coatings or fillings and are fully natural.

Avoid harsh chemicals.
Clean with warm water, mild soap, and a soft brush.
Spinel is safe for ultrasonic cleaning.
Store separately from harder stones like sapphire or diamond.

Major sources of spinel include:

Myanmar (Burma)
Sri Lanka
Tanzania
Vietnam
Madagascar
Tajikistan