The Enchanting World of Spinels: From Formation to Rarity

Spinels, with their captivating colours and intriguing properties, have long been a gemstone of fascination. Born deep within the Earth's crust, spinels are created through a complex process that results in their unique beauty. Let's explore the geology of spinels, their global locations, historical significance, quality factors, and treatments. We'll also delve into the most valuable and sought-after colours of spinel, including neon blue cobalt spinels, vivid red spinels, lavender spinels, and the rare fluorescent "Jedi spinels".

Geology and Formation of Spinels:

Spinels belong to the family of oxide minerals and are composed primarily of magnesium-aluminium oxide. They are typically formed in metamorphic and igneous rocks under high-pressure and high-temperature conditions. These gemstones crystallise in octahedral and cubic shapes, lending them a distinct geometric beauty. The geological forces that shape spinels occur over millions of years, resulting in the creation of these exceptional gemstones.

Locations of Spinels:

Spinels can be found in various regions around the globe, each offering unique variations in colour and quality. Tanzania, particularly the Mahenge region, has gained recognition in recent years for its remarkable spinel discoveries. The spinels unearthed in Mahenge exhibit a wide range of colours, from neon blues to vivid reds, and are highly sought after by gemstone enthusiasts and collectors. Burma, known for its rich gemstone heritage, has long been renowned for its exceptional spinels. Other notable sources of spinels include Vietnam, Sri Lanka, Madagascar, and Tajikistan, each with their own characteristic colorus and qualities.

5.64ct Blue Spinel from Madagascar with interesting rutile inclusions

Historical Significance:

Throughout history, spinels have held a significant place in the world of gemstones. They were often mistaken for other gemstones, including rubies. For instance, the "Black Prince's Ruby" in the British Crown Jewels and the "Timur Ruby" in the British Royal Collection were later identified as spinels. These historical misidentifications have only added to the allure and mystique surrounding spinels.

 

Quality Factors and Treatments:

When evaluating spinels, several factors contribute to their quality and value. Colour is perhaps the most crucial aspect, with intense and saturated hues being highly desirable. Spinels occur in a broad spectrum of colours, ranging from deep blues and vibrant reds to lavender shades. The most prized spinels exhibit exceptional clarity and brilliance, free from visible inclusions. As a general rule, spinels are typically not subjected to treatments, as their natural colours are highly prized. However, it's important to note that treatments such as heat may be used to enhance their appearance or minimise any visible flaws.

Neon Blue Cobalt Spinels:

Among the most valuable and sought-after spinels are the rare neon blue cobalt spinels. Found primarily in Sri Lanka, Vietnam and more recently Mahenge in Tanzania, these spinels exhibit a vibrant blue hue, often likened to the mesmerising shades of sapphires. Their intense colour saturation and exceptional glow make them highly desirable to gem collectors and jewellery designers.

Cobalt Spinels from Luc Yen in Vietnam

An Phú, located near Luc Yen in Vietnam, is globally renowned as the sole location where the most highly coveted neon-tone gemstone, known as the most desirable of all gem blues, can be found. The quantity of this captivating gem is incredibly scarce, making even a decent, flawless gem weighing half a carat a rarity in itself. Any gemstone weighing one carat or more becomes an immediate target for seasoned gem collectors due to its exceptional beauty and scarcity, for this reason the finest gems from this location sell for many tens of thousands dollars per ct.

Cobalt Spinels from Mahenge, Tanzania:

In a thrilling discovery last year (2021), Mahenge, Tanzania, unveiled a new source of cobalt spinels. These gems, known for their captivating blue shades, have sparked significant excitement within the gemstone community. With their brilliant neon-like glow and exceptional color consistency, cobalt spinels from Mahenge are rapidly gaining recognition as some of the most coveted gems in the world.

Cobalt Spinels of 1.2ct, 0.86ct and 1.18ct from Mahenge, Tanzania 

Vivid Red Spinels:

Burma, Mahenge, Tajikistan, and Vietnam are renowned for producing vivid red spinels. These gems exhibit intense red hues, ranging from deep crimson to fiery scarlet. The Burmese spinels, in particular, are highly prized for their rich red colour and historical significance. Burmese spinels have a long-standing reputation for their exceptional quality and rarity.

Cut and rough Red Spinels from Mogok, Burma.Photo by Vincent Pardieu, courtesy of Gübelin Gem Lab.

Lavender Spinels:

Lavender spinels, known for their delicate and enchanting hues, can be found in Burma, Sri Lanka, Madagascar, Vietnam, and Tanzania. These spinels possess a soft lavender or lilac colour that exudes elegance and sophistication. The pastel tones of lavender spinels make them a popular choice for those seeking a more subtle and feminine gemstone.

Pink Spinels:

Pink spinels are cherished for their delicate and romantic colour. They can be found in Mahenge, Tanzania, Burma, Vietnam, Sri Lanka and Madagascar. These pink spinels range from soft pastel pinks to more vibrant and saturated shades.

Rare Fluorescent Jedi Spinels:

Among the most unique spinels are rare fluorescent spinels, that have been labelled "Jedi spinels" by the trade. These spinels, characterised by their vibrant red or pink colours and strong fluorescence, possess a captivating neon-like glow.

1.89ct Vibrant Pinkish Red Spinel, from Mansin, Burma.

What sets Jedi spinels apart is their very low iron content, which contributes to their open bright colours and distinctive fluorescence. These extraordinary gemstones are predominantly unearthed in two regions: Mahenge in Tanzania and Mansin and Namya in Burma. Notably, the term "Jedi spinels" was coined by the esteemed field gemologist Vincent Pardieu upon his initial discovery of these exceptional gems in Burma. Over time, this designation has become a trade term to describe these gems, and has expanded to encompass equally exquisite gemstones from Mahenge in Tanzania. As a result, Jedi spinels have gained substantial recognition, surging in both popularity and value

Fine " Jedi " spinels from Man Sin, Burma. The seven faceted stones on the left have a total weight of 12.9 ct, while the two clean crystals weigh 3.9 and 3.3 ct. Photo by Vincent Pardieu, © GIA.  

The Future of Spinels:

As spinels continue to captivate gem enthusiasts and collectors worldwide, their future looks promising. Their unique colours, geological origins, and historical significance contribute to their growing appeal. With increasing awareness of spinels and a focus on responsible sourcing, these gemstones offer an ethically sound alternative to other precious stones. As demand for spinels rises, their value and appreciation in the market are likely to follow suit.

Whether it's the mesmerising neon blue cobalt spinels, the fiery reds, the delicate lavenders, or the rare fluorescent Jedi spinels, spinels offer a kaleidoscope of colours and a touch of intrigue. From their formation deep within the Earth to their discovery in diverse locations across the globe, spinels continue to amaze and inspire. As you explore the world of gemstones, don't overlook the enchanting allure of spinels, for they hold within them a captivating story and a beauty that is truly timeless.