18th Century gemologist Jean Baptiste Louis Rome de Lisle must have caused quite the stir in 1783 when he identified the spinel as a different type of gemstone, separate from the category of “ruby” to which the jewelry community classified previously discovered spinels.
Why? Some of the most popular stones in the world at that time had to change categorization from rubies to spinels.
Two of the most famous gemstones that fell prey to this switch in taxonomy are the Black Prince’s Ruby and the Timur Ruby. The Black Prince’s Ruby is a large stone that sits in front of Great Britain’s Imperial State Crown, while the Timur Ruby is another large piece that is now part of the Crown Jewels of the UK. The Timur Ruby previously exchanged hands amongst rulers of ancient Turko-Mongol empires.
Spinels were first identified as different from rubies by 16th-century gem traders in Myanmar and India. Plus, gem historians speculate that Turko-Mongol rulers (to whom spinel stones were prized possessions) knew the difference between both gemstones too.
However, spinels continued to be misidentified as rubies in Europe and the rest of the world until 1783, when modern gemology caught up to the difference.
Like with most forms of change, this new development created some anxiety and brought up several questions in the minds of jewelers accustomed to the former established order. How are spinels different from ruby? Are they as rare or as valuable? What even is a spinel, really?
Today, with the rise in the popularity of black gemstones like the black diamond, one member of the infamous spinel family, the black spinel is getting a great deal of the spotlight.
What is A Black Spinel Gemstone
Although spinels have appeared in much high-status jewelry since ancient times, the only recently, with the advent of modern gemology, got their own category. Previously, people considered spinel gemstones to be rubies, and there is a good reason why.
Spinels are rare gemstones that consist of magnesium aluminum oxide, while the primary building block of rubies is aluminum oxide. Hence, both rubies and spinels bear almost identical makeups, with the main difference being the presence of magnesium.
For this reason, rubies and spinels often occur in the same spots.
The mining of spinels and rubies often happens concurrently, as both gemstone types often occur side by side at mine sites.
Some of the most common locations that produce spinel gemstones (and rubies) include mines in Burma, Cambodia, Sri Lanka, Thailand, Nepal, Afghanistan, Vietnam, Madagascar, and Nigeria.
Both gemstone types also share a similar appearance at first glance, as both stones share identical colors and pack considerable luster.
Rubies and spinels get their color from trace elements like chromium, which gives them a red hue, nitrogen, which can cause a yellow tint, and graphite, which can create darker shades like in blue and black spinels.
However, a trained eye can quickly tell the difference between spinel and a ruby on a closer look.
Rubies have a trigonal crystal structure and are dichroic, which means that they fluoresce in the presence of light, spewing different colors in all directions. On the other hand, spinels have a singly refractive structure like diamonds, so you get more vivid color and relatively higher brilliance here. Spinels generally also occur in larger crystals than rubies and sapphires.
Spinels (from ‘spina,’ Latin for ‘thorn’) get their name from their angular crystal formations.
Black spinels are one of the rarest gems in the spinel family, and one of the less sought after options, especially compared to the more famous red variant. However, black spinels do have a market of their own amongst black gemstone enthusiasts.
Black Spinel Properties
The properties that set black spinels apart from many other types of gemstones include their:
Spinels are considerably hard, and they post a Mohs hardness level of 8, tougher than quartz and feldspar, but slightly softer than rubies and sapphires at 9, and diamonds at level 10.
Because of their toughness, you can clean spinel gemstones with soapy water and a soft cloth, and polish them without scratching the surface.
Due to their relative softness, spinels are significantly easier to manipulate. Hence, you can often find black spinels and other spinel types in different types of faceted and intricate shapes and cuts.
Spinels exude a vitreous glass-like luster, unsurprising, considering its relatively transparent structure and low refractive index. Black spinels keep this same high reflectivity, even with its darker shade.
However, unlike black diamonds and labradorite, black spinels do not give off a metallic overtone.
Spinels often feature relatively transparent structures and rarely have inclusions. However, when they do have inclusions, an asterism (star reflection effect.) Black spinels with asterism can make for some of the most unique looking gems.
Black Spinel Gemstones Market Value
Despite their rarity, spinels do not pack as much market value as similar gems like rubies and sapphires. Amongst spinels, black spinels also hold a lower position price-wise to the more sought-after red variants.
Experts consider this disparity in price due to the relatively low demand, stemming from the lack of awareness of many consumers who consider spinels second fiddle to rubies.
However, the tide is turning with more educated consumers beginning to appreciate the spinel for its natural beauty.
Unsightly inclusions can significantly degrade the price of spinels.
Their relatively modest prices and their malleability (which make them suitable for multiple jewelry types) make spinels like the black spinel an excellent option for everyday jewelry and a favorite amongst informed buyers who consider these gemstones to be currently undervalued.
Spinels are considerably affordable, with market prices for most standard offerings ranging between $200 to $500 per carat. However, top spinels can retail for as high as $1200 per carat, while rare, large stones can sell for upward of $8,000 per carat.
The most valuable forms of spinels are faceted stones.
Are black spinel gemstones natural?
Yes, most black spinel stones are naturally-occurring. While synthetic spinels are available too, they are mostly colorless or whitish green.