Last updated on September 6, 2023
When it comes to gemstones, blue spinel and sapphire are often compared due to their similar appearance. Both are known for their brilliant blue colour and are highly valued in the world of gemstones. However, despite their similarities, some key differences between the two stones are worth noting. In this article, we will take a closer look at blue spinel vs blue sapphire and help you understand the unique qualities of each.
Blue Spinel vs Blue Sapphire Formation
Blue spinel and blue sapphire are formed under different geological conditions, which result in unique properties that distinguish them from each other.
Blue spinel can form in various geological environments, including igneous, metamorphic, and sedimentary rocks. In igneous rocks, blue spinel can form as a primary mineral during the cooling of magma. In metamorphic rocks, blue spinel can form as a result of the alteration of other minerals under high-pressure and high-temperature conditions. Blue spinel can also be found in alluvial deposits where it is transported and deposited by water.
On the other hand, blue sapphire is a variety of corundum and forms in a range of geological environments, including metamorphic rocks and pegmatites. The formation of blue sapphire requires specific conditions, including high pressure and high temperature. In metamorphic rocks, sapphire can form during regional metamorphism when rocks are subjected to intense heat and pressure. In pegmatites, sapphire can form when hot fluids that contain dissolved minerals cool and solidify.
Blue Spinel vs Blue Sapphire Colour
Blue spinel and blue sapphire are two popular gemstones prized for their beautiful blue colour. While they may appear similar at first glance, there are some distinct differences between the colours of these two gemstones.
The blue colour of spinel is due to the presence of trace amounts of cobalt, which can be incorporated into the crystal structure during the mineral formation process. The concentration of cobalt can vary, resulting in different shades of blue.
The colour of blue spinel tends to be more muted and subtle than that of blue sapphire. Spinels often have a soft, gentle blue shade that can be quite attractive in its own right.
On the other hand, blue sapphire is known for its vivid and intense blue colour, which is caused by the presence of trace amounts of iron and titanium during the mineral formation process. The concentration of these elements affects the intensity of the blue colour in sapphire, with higher concentrations resulting in more saturated and vibrant blue. The finest blue sapphires have a rich, velvety blue colour that is highly prized in the gemstone market.
Blue Spinel vs Blue Sapphire Clarity
Blue spinel is generally considered to be a clean and transparent gemstone with good clarity. However, like all gemstones, spinel can contain inclusions or flaws that can affect its appearance and value. These inclusions may include tiny cracks, bubbles, or mineral inclusions that can detract from the gemstone’s clarity.
In some cases, blue spinel may exhibit silk, which refers to fine needle-like inclusions that can create a soft, velvety appearance when viewed under magnification. Silk can sometimes enhance the value of spinel if it is present in a way that enhances the gemstone’s appearance.
Blue sapphire is also known for its good clarity, which is an important factor in determining its value. Like blue spinel, sapphire can contain inclusions or flaws that can affect clarity. Some common inclusions in sapphire include feathers, crystals, and mineral inclusions.
One notable inclusion in sapphire is called rutile silk, which refers to thin needles of rutile that are trapped inside the sapphire crystal. When viewed under magnification, rutile silk can create a hazy or silky appearance that can enhance the value of the sapphire.
Blue Spinel vs Blue Sapphire Durability
When it comes to durability, blue spinel and blue sapphire are both excellent choices for jewellery because they are durable gemstones that can withstand daily wear. However, there are some differences between the two in terms of their hardness and durability.
Spinel is a hard gemstone with a rating of 8 on the Mohs hardness scale, which means it is a relatively hard and durable stone that can resist scratches and other forms of wear. However, spinel can still be damaged if subjected to excessive force or impact, such as dropping or hitting a stone. It is also important to note that spinel can be brittle, so it may be more susceptible to cracking or chipping than some other gemstones.
Sapphire, on the other hand, is one of the hardest and most durable gemstones, with a rating of 9 on the Mohs hardness scale. This makes it one of the most scratch-resistant gemstones available, and it can withstand a wide range of wear and tear without showing significant signs of damage. However, it is still important to care for your blue sapphire jewellery properly to avoid any potential damage or harm.
Blue Spinel vs Blue Sapphire Availability and Price
When it comes to availability and price, there are some significant differences between blue spinel and blue sapphire.
Blue sapphire is a relatively common gemstone widely available in many parts of the world, including Sri Lanka, Madagascar, and Thailand. As a result of its widespread availability, blue sapphire is relatively easy to source and is offered in a wide range of qualities, sizes, and cuts.
Blue spinel, on the other hand, is a much rarer gemstone and is found in relatively small quantities in limited locations such as Myanmar, Sri Lanka, and Tanzania. As a result of its limited availability, blue spinel is much harder to source than blue sapphire, and high-quality blue spinel specimens are highly sought after by collectors and enthusiasts.
However, despite the differences in availability, blue spinel is generally less expensive than blue sapphire, especially when comparing high-quality specimens. This is due to the differences in demand for the two gemstones. Blue sapphire is a much more popular and widely recognized gem, and as a result, it commands a higher price than blue spinel. Additionally, high-quality blue spinel specimens are much rarer than blue sapphires, which can drive up their price. However, in general, blue spinel is considered a more affordable alternative to blue sapphire and is often used as a substitute in jewellery.
Blue Spinel vs Blue Sapphire Properties
|BLUE SPINEL||BLUE SAPPHIRE|
|Chemical Name||Magnesium aluminum oxide||Aluminium oxide|
|Colours||Muted and subtle blue||Saturated and vibrant blue|
|Hardness||8 on the Mohs scale||9 on the Mohs scale|
|Refractive Index||1.71 - 1.73||1.76 - 1.78|
|Specific Gravity||3.54 ~ 3.63||3.95 - 4.03|
|Transparency||Transparent to opaque||Transparent to opaque|
Featured image: Blue spinel image - galka3250 / Shutterstock, blue sapphire image - Luen Wantisud / Canva. A derivative work by Diamond Buzz.