Ruby and spinel are two of the most sought-after, historical, and contemplated gemstones in the world. They’ve been revered and contemplated throughout life because of their remarkable physical and optical properties and strong resemblance. These two gemstones are also the most significant discoveries in the history of gemstone mining; we’ll talk about that in a while. Let’s first try to compare the two gemstones based on chemical composition, color, hardness, and price.
A traditional jewelry stone, ruby is a variety of the mineral corundum, a crystalline form of aluminum oxide (Al2O3). This mineral crystallizes in slow-cooling igneous or metamorphic rocks with a precise set of ingredients. High proportions of aluminum (AI) and a lack of silicon (SI) results in the formation of corundum in the raw crystal. However, because silicon is one of the most common elements in the earth’s crust – for perspective, oxygen and silicon together constitute more than 74% of the earth’s crust – the formation of corundum is unique.
On the other hand, spinels are a subset of a large group of related magnesium aluminum oxide mineral species. Magnesium, iron, zinc, and traces of some other elements make up the crystalline structure of these species.
Ruby occurs in all varieties of red, from pinkish, purplish, orangey and brownish to dark red. People covet the ruby gemstone because it glows in the sunlight like nothing else does because of its red fluorescence. Though rubies don’t occur in other colors except red, color is the most significant factor for determining the value of a ruby gemstone. Pure red color rubies command the highest prices of this gemstone. Ruby’s appealing red color is attributed to the presence of chromium in trace proportions in the mineral.
Chromium causes variations in color in the mineral ranging from orange-red to deep purple-red; in fact, what strengthens the color of a ruby gemstone is the intensity of the presence of this trace element in the mineral’s crystal structure. So, the more intense the presence of chromium in the mineral, the stronger the color of the ruby.
While rubies only occur in different varieties of red, spinels occur in various shades of red, blue, pink, orange, brown, lavender, black, gray, purple, lilac, red-orange, rose and light green. Some very rare spinels are also colorless. Despite having a wide and impressive array of color options, the spinel gemstone is long known best as an imposter of ruby. However, spinel is a lovely gemstone in its own right. The many color options of this gemstone make it an excellent jewelry stone. As with ruby and other gemstones, spinel also gets its color from different trace elements like chromium, iron and cobalt, to name a few.
The presence of chromium and its intensity in the mineral’s crystal structure results in either orange, pink, or red spinels. Similarly, green spinel owes its color to the presence of the trace element iron in the mineral. Because of the overwhelming advantage of the many color options, the spinel gemstone outdoes ruby in terms of color.
Resistance To Scratching
Among natural gemstones, the ruby gemstone has an extreme hardness level that’s second only to that of diamond. Ruby has a hardness of 9 on the 10-point Mohs scale of hardness, meaning it offers commendable resistance to scratching, thus great wearability. Rubies don’t even have cleavages, making them superb jewelry stones that can be worn every day. Gemstone cleavage is a tendency of certain crystals to break when struck. Since rubies don’t have cleavage, these gemstones have excellent toughness.
Much like rubies, spinels also lack cleavage and thus make good jewelry stones. The spinel gemstone provides superior resistance to blows and scratches and has a hardness score of 7.5 to 8 on the Mohs scale of hardness. Ruby does exceed spinel as regards hardness, but the difference between their hardness scores is too little to dissuade one from investing in the latter. I mean, with a hardness score of 7.5 to 8 on the Mohs hardness scale, spinel sounds just about ideal for jewelry pieces subjected to daily wear.
Ruby and spinel are two important gemstone discoveries that framed the world of gemology. For centuries, people have misidentified spinel as ruby, especially in Europe, Asia, and the Middle East. Unless you’re the uninitiated, you know that some of the world’s most famous rubies were not rubies but spinels. Back in the day, people used to classify spinel gemstones as rubies out of sheer ineptitude in distinguishing between these two gemstones.
Ruby and spinel are two important gemstone discoveries because distinguishing between these two gemstones led to the inception of the world of gemology. In 1783, French physicist and mineralogist, Jean-Baptiste Louis Romé de L’Isle, distinguished spinels as distinct mineral species. In that sense, ruby and spinel gemstones should command the highest per-carat prices of all the gemstones. However, that’s not the case. On the contrary, the per-carat prices of rubies are much more than those of spinels, other things being equal.
This difference in the per-carat prices of spinel and ruby gemstones can be attributed to the fact that rubies have long enjoyed the prestige born out of not only their beautiful shades of red but also the inability of people to separate spinels from rubies. I mean, all those esteemed rubies that were actually spinels – the Black Prince’s ruby and the Timur ruby, to name a few – indeed contributed a lot to the widespread adulation of rubies.
An Unfavorable Comparison
For most of its life, spinel has been known as ‘the great imposter’. This pejorative name was christened to the gemstone because of its checkered past. And it’s only because of this checkered past of spinels that these gemstones shouldn’t be compared to rubies. I mean, both rubies and spinels are beautiful gemstones in their own right, but because one of them has had an undue advantage over the other, they can’t be compared.