Spinel vs Ruby: How to Tell the Difference Between These Gemstones

Introduction

Are you a jewelry buyer, collector, or gemstone enthusiast trying to distinguish between spinel and ruby? This article is your comprehensive guide to understanding the key differences between these two stunning red gemstones. Knowing how to tell spinel from ruby is crucial for making informed purchases, protecting your investment, and appreciating the unique qualities of each stone.

Spinel Vs Ruby: Best Tips to Distinguish These Gemstones

Gemstones may look alike but differ in origin, colour, physical properties, and market value. Historically, people often misidentified spinel as ruby because of its similar appearance. A famous example is the ‘Black Prince’s Ruby’ in the British Crown Jewels, which was later revealed to actually be a spinel. Many famous 'rubies' in crown collections were later confirmed to be spinels. Spinel was historically mistaken for ruby due to its vibrant red hue, closely resembling the prized colour of rubies. This guide will help you understand these distinctions and confidently identify and choose between them. Red spinel was historically overlooked and not recognized for its true value compared to ruby, despite being highly regarded in Europe, often mistaken for rubies and popular among royalty, frequently used in regal jewelry. Spinel was highly prized in the Middle Ages and favoured by the nobility for regal jewellery. In 1783, spinel was officially distinguished as a separate mineral species from ruby. This article compares spinel and ruby, highlighting their differences in colour, origin, properties, and value.

Spinel vs Ruby: Summary Comparison Table

Introduction to Red Gemstones

Red gemstones have long been associated with passion, love, and power, making them among the most coveted in the world of jewelry. Among both stunning red gemstones, ruby and spinel stand out for their vibrant colour and fascinating histories. Ruby, a variety of the mineral corundum, is celebrated for its deep red, pigeon blood hue—a shade that has become the gold standard for red gemstones. Spinel, a distinct mineral species, offers a remarkable spectrum of red shades, from pinkish red to reddish orange, and is often mistaken for ruby due to its similar appearance. These stunning red gemstones have adorned royal collections and continue to captivate collectors and jewelry lovers alike. Whether set in a classic ring or a modern pendant, ruby and spinel bring a rich red colour and timeless elegance to any piece of jewelry.

Now, let's look at some key differences in their origins and colour:

Origins:

• Rubies form in metamorphic environments and emerge from metamorphic and magmatic processes.

• Spinels can form from both metamorphic and magmatic processes and are commonly found in limestones and ultramafic rocks.

Colour Differences:

• Ruby is usually bright red, with shades ranging from pinkish-red to deep blood-red.

• Spinels come in a wider range of colours, including red, blue, pink, orange, and black, making proper identification challenging.

Clarity, chemical composition, and market value significantly influence the desirability and pricing of rubies and spinels. Due to their rarity, rubies generally command higher prices. Ruby has a hardness rating of 9 on the Mohs scale, making it one of the hardest gemstones.

Understanding the Origins of Ruby and Spinel

Rubies typically form in metamorphic environments such as marble and schist, with Burma (now Myanmar) historically recognized as the most renowned source. Natural rubies, especially those that are untreated and possess exceptional colour, are highly valued and rare compared to treated rubies and other gemstones like spinels. The most valuable rubies are those that are a deep, rich red colour with excellent clarity and very few inclusions. High-quality ruby prices continue to rise due to increasing difficulty in finding stones of this quality.

Spinels can form from both metamorphic and magmatic processes. They were first discovered in ancient Sri Lanka. Spinel is commonly found in limestones that have undergone metamorphism and in ultramafic rocks such as peridotite. Their distinct characteristics and value are shaped by their geological and historical contexts. Spinel is typically highly transparent, allowing for easy spotting of blemishes or inclusions within the gemstone. Additionally, spinel has a vitreous lustre and is known for its excellent transparency. Tools and instruments, such as a dichroscope and a jeweller’s loupe, can help distinguish between rubies and spinel.

Geological Formation

Rubies are primarily found in metamorphic rocks such as marble and schist. The presence of chromium causes their vivid red colour. Trace amounts of chromium are responsible for the red coloration in both ruby and spinel, influencing the intensity and hue of each stone.

Classified as a distinct mineral species by Jean-Baptiste Louis Romé de L’Isle in 1783, spinels are sourced from regions like Myanmar, Sri Lanka, Vietnam, and Tanzania. The unique geological conditions in these areas enhance their formation, value, and allure.

Historical Context

Ancient civilizations like the Egyptians and Romans highly valued rubies and spinels for their protective powers. The Black Prince's Ruby, a famous spinel mistaken for a ruby, highlights the historical confusion between these two gemstones. The name refers to the optical doubling effect in rubies, which often led to misidentifications. Vibrant red spinels were frequently referred to as ‘ruby spinel' due to their striking resemblance to rubies.

Frequent misidentification of spinels as rubies and sapphires earned them the nickname ‘the great imposter.' These anecdotes underscore the enduring allure and mystery of these gemstones.

Now that we've explored their origins, let's examine how their colours set them apart.

Colour Differences Between Ruby and Spinel

One of the most striking differences between ruby and spinel is colour. Rubies are primarily bright red, with shades ranging from pinkish-red to deep blood-red, often called ‘pigeon’s blood red.’ The finest rubies exhibit this deep red hue, commonly known as ‘pigeon blood’ red, which is highly sought after and commands the highest market prices. Ruby’s strong red fluorescence gives it a beautiful glow under certain lighting conditions.

Conversely, spinels come in a broader colour range, including red, blue, pink, orange, and deep black. Intense reds and pinks are particularly prominent. Spinels are typically highly transparent, allowing easy inspection for blemishes or inclusions. When comparing the red varieties, there are subtle differences in the shades of red between spinel and ruby. Spinel's hue is slightly softer and less intense compared to the vivid, saturated red of ruby.

These colour characteristics help differentiate the two gemstones. How light interacts with these gems affects their colour and visual appearance; rubies and spinels exhibit distinct refractive properties.

Ruby Colour Characteristics

• Strictly red, with shades from orangey-red to purplish-red

• Deep, saturated “pigeon blood” red is most prized

• Strong red fluorescence under UV light

• Colour comes from chromium in its structure

Spinel Colour Characteristics

• Wide colour range: red, pink, purple, blue, black, orange

• Red spinel often has a slightly orangey or pinkish-red hue

• Typically highly transparent, with excellent brilliance

• Colour can be vibrant and bright, sometimes mistaken for ruby

Key Colour Differences (Bullet Points)

• Ruby:

  • Strictly red, with deep, purplish or orangey undertones

  • More intense, saturated colour

  • Strong fluorescence

• Spinel:

  • Wider colour range (red, pink, purple, blue, black)

  • Softer, sometimes brighter or pinkish-red

  • Less intense fluorescence

Primary Colors

Chromium largely influences the vivid red colour of rubies, giving them prized deep blood-red and pinkish-red hues. Spinels can exhibit a variety of colours, including red, blue, pink, purple, and black, making them versatile for a range of jewelry designs. For comparison, red garnet is another red gemstone, with varieties such as pyrope and almandine, and its colour can range from deep red to reddish-brown.

This colour diversity can make distinguishing between red spinel and ruby challenging without professional training.

Secondary Hues and Inclusions

Due to different trace elements, secondary hues in rubies can range from purplish to orangey-reds. They also have unique internal features called ‘fingerprints’ that distinguish them from spinels, which generally lack such inclusions. Additionally, rutile needles are a common type of inclusion found in ruby, and their presence can help further distinguish ruby from spinel.

Identifying these secondary hues and visible inclusions is essential for gemologists and collectors to accurately distinguish rubies from spinels.

With colour differences clarified, let's move on to the physical and chemical properties that further set these gemstones apart.

Physical and Chemical Properties of Different Trace Elements

Rubies and spinels’ physical and chemical properties offer a scientific basis for their distinctiveness. Both are durable, but rubies are slightly harder and more scratch-resistant. Ruby's high hardness makes it especially durable for everyday wear, while spinel's hardness is slightly lower but still suitable for jewelry due to its good toughness and resistance to breakage. On the other hand, synthetic rubies are generally clearer and free of the inclusions found in natural rubies, which can affect perceived quality. Rubies have a refractive index of 1.76-1.78, which contributes to their brilliance. Spinel, with a refractive index ranging from 1.712 to 1.736, also exhibits significant brilliance, making it a captivating choice for jewelry.

The unique chemical compositions and crystal structures of these gemstones further distinguish them. Spinel's colour is caused by the presence of iron and chromium. However, exposure to harsh chemicals or abrasive materials can cause scratches and chips on rubies and spinels, underscoring the importance of proper care.

Ruby is aluminum oxide (Al2O3) with a Mohs hardness of 9, while spinel is magnesium aluminum oxide (MgAl2O4) with a hardness of 8.

Ruby Hardness and Durability

• Mohs hardness: 9 (extremely hard and scratch-resistant)

• Excellent for everyday wear and high-contact jewelry

• High durability and investment potential

Spinel Hardness and Durability

• Mohs hardness: 8 (very durable, but slightly softer than ruby)

• Lacks cleavage, making it resistant to breakage

• Suitable for daily wear and larger jewelry pieces

These properties make both rubies and spinels excellent choices for durable gemstone jewelry, but it's also important to consider the environmental impact of mined gemstones.

Crystal Structure and Composition

Ruby is a variety of the mineral corundum, formed in metamorphic and igneous rocks. Ruby is aluminum oxide (Al2O3) with a Mohs hardness of 9, while spinel is magnesium aluminum oxide (MgAl2O4) with a hardness of 8. Rubies are composed of aluminum oxide (Al2O3) with chromium impurities, whereas spinels, which consist of magnesium and aluminum, have a chemical formula of MgAl2O4. Rubies form under high-pressure, high-temperature conditions, which distinguish their crystal structure and composition. The word 'ruby' comes from the Latin word 'ruber,' meaning red. Ruby is one of the four precious gemstones, along with diamonds, emeralds, and sapphires.

Spinel is a magnesium-aluminum oxide mineral formed in metamorphic and igneous rocks.

These differences in crystal structure and composition are key to distinguishing the two gemstones.

With a clear understanding of their physical and chemical properties, let's look at how treatments and enhancements affect their value and appearance.

Treatments and Enhancements

In the world of gemstones, treatments and enhancements are commonly used to improve a stone’s appearance and value. Rubies are frequently heat-treated to intensify their colour and clarity, making them more visually appealing and, in many cases, more valuable. However, untreated rubies—especially those with exceptional colour and clarity—are incredibly rare and command premium prices. Spinel, by contrast, is prized for its natural brilliance and vibrant colour, and high-quality spinels typically do not require any treatments. This natural beauty allows spinel to rival ruby in terms of visual appeal, especially those stones that display exceptional colour and clarity straight from the earth. For collectors and buyers, knowing whether a gemstone has been heat-treated or remains in its natural state is crucial, as untreated rubies and high-quality spinels are considered the most desirable and valuable.

Now that we've covered treatments, let's explore how clarity and inclusions impact the value and appearance of these gems.

Clarity and Inclusions

Clarity and inclusions significantly impact the appearance and value of rubies and spinels. As one of the four precious gemstones, rubies have been valued and culturally significant throughout the ages. Rubies typically contain more inclusions than spinels, leading to a less uniform appearance. Spinel generally has fewer inclusions, resulting in higher transparency and a cleaner appearance. The visibility and type of inclusions can greatly affect the value and desirability of these gemstones.

Typical Inclusions

Rubies often exhibit liquid inclusions, such as fingerprints and discoid fractures, which reduce clarity. Conversely, spinels can display unique optical features, such as pleochroism and two-phase inclusions. Due to their octahedral crystal growth, spinels sometimes resemble human fingerprints. Spinels can exhibit pleochroism, displaying different colours at different angles, further enhancing their visual appeal and distinguishing them from rubies.

These inclusions help gemologists and collectors identify and authenticate these gemstones.

Impact on Value

Inclusions can significantly lower the value of rubies by affecting their clarity and aesthetic appeal. While still important, inclusions in spinels may have less impact on pricing than rubies. High-quality gemstones with fewer visible inclusions are more sought after and command higher market prices.

With clarity and inclusions explained, let's move on to how gemologists use test weight and density to distinguish these stones.

Test Weight and Density

Test weight and density are important tools for gemologists when identifying and evaluating gemstones. Ruby and spinel, while similar in appearance, have distinct densities—ruby is slightly denser than spinel. This subtle difference can be a key factor in distinguishing between the two, especially when comparing gemstones of the same size and shape. By carefully measuring the gemstone's weight and calculating its density, experts can confirm whether it is a ruby or a spinel, helping prevent misidentification. This process is particularly useful in the gemstone market, where authenticity and accurate identification are essential for both buyers and sellers. Understanding the test weight and density of ruby and spinel helps collectors and jewelry enthusiasts invest in genuine, high-quality gemstones.

Now that you know how to physically identify these gems, let's see how their market value and pricing compare.

Market Value and Pricing

Several factors, including rarity, size, carat weight, gemstone quality, and treatment, influence the market value and pricing of rubies and spinels. Carat weight plays a significant role in determining value and rarity—larger stones and larger sizes are much rarer in ruby, especially in sizes over 5 carats, and command much higher prices per carat. Fine-quality rubies are much rarer than spinels, particularly in larger sizes, making them highly sought after by collectors and investors.

Ruby jewelry is highly appealing as a classic and luxurious choice, with ruby’s longstanding dominance in the jewelry market due to its beauty, durability, and high value. Rubies are among the most expensive gemstones, with prices ranging from $10,000 to $100,000+ per carat, and rubies command some of the highest prices per carat in the gemstone market. Ruby has long dominated the market as a symbol of luxury jewelry, especially Burmese rubies that can fetch astronomical prices. Ruby has been featured in numerous high-end jewelry pieces and auctions, further cementing its status as a symbol of luxury and prestige. Most rubies undergo heat treatment to improve their appearance and enhance their colour and clarity.

While some spinels can be quite valuable, most red spinels are considerably less expensive than a ruby of comparable quality. Spinel offers a lower cost and more affordable alternative to ruby, especially for those seeking impressive, larger sizes or larger stones, as red spinel over 5 carats is more available and less expensive per carat than ruby. As demand for spinel increases, its prices are slowly rising, but it remains a cost-effective and visually appealing choice for buyers. Gemstone quality also significantly affects the price differences between rubies and spinels, with higher quality stones commanding higher prices in both categories.

For long-term investment, ruby is generally the better option due to its rarity and high value.

Understanding these factors is crucial for investing in these beautiful gemstones.

Factors Affecting High Prices

The origin of a ruby is crucial for its valuation, with Burmese rubies being the most sought-after for their quality. High-quality spinels without visible inclusions are significantly more valuable than those with flaws.

High-quality rubies with deep red colour and excellent clarity are incredibly valuable. The most valuable rubies display a deep red hue, often called 'pigeon blood' red. Additionally, untreated rubies command higher prices than heat-treated rubies.

Market Trends

High-quality rubies continue to see increasing demand as investment pieces. Both rubies and spinels are highly sought after in high-end jewelry markets, appealing to collectors for their unique colours and rarity.

Spinels are generally more abundant and affordable than rubies of comparable quality, making them popular among jewelry enthusiasts.

With market value in mind, let's explore the astrological and symbolic significance of these gemstones.

Astrological and Symbolic Significance

The astrological and symbolic significance of rubies and spinels adds emotional and cultural value to these stones. Rubies symbolize love and passion, making them meaningful choices for engagement rings. Rubies are the traditional birthstone for July, while spinel was added as an official birthstone in 2016 for August.

Spinels also hold significant astrological and symbolic meanings, enhancing their appeal.

Astrological Benefits

In Hinduism, rubies are seen as the ‘king of precious stones' associated with powerful rulers and protection from harm. Spinels, linked to zodiac signs like Aries, Scorpio, Taurus, and Sagittarius, are believed to promote emotional stability and creativity.

These astrological benefits make these gemstones popular among those seeking spiritual and emotional balance.

Symbolism and Cultural Importance

For centuries, rubies have been culturally significant. They are often associated with royalty and used in royal jewelry to symbolize power and wealth. Rubies represent passion, love, and courage and are believed to enhance vitality, leadership, and success. Ruby has been cherished for centuries, holding a prominent place in royal jewelry across global empires. Rubies were often believed to possess magical powers and offer protection against evil spirits in ancient civilizations.

Linked to the planet Mars, red spinels are believed to amplify martial energy and are increasingly recognized for their beauty and rarity.

With their symbolic significance established, let's see how these stones are used in modern jewelry.

Popular Uses in Jewelry

Rubies and spinels are frequently used in high-end jewelry, including engagement rings, fine jewelry, and collectibles. Their vibrant colours and durability make them popular among jewelry enthusiasts.

Engagement Rings

Rubies are increasingly chosen for engagement rings for their vibrant red hue and symbolic meaning of love. Spinels offer a unique, affordable alternative, making them popular among those seeking a durable, beautiful gemstone for their ring.

Both gemstones are frequently used in statement pieces for their captivating colours, including ruby.

Fine Jewelry and Collectibles

Historically, rubies and spinels have adorned royal jewelry, symbolizing power and wealth. Both are highly sought after for high-end jewelry, and spinels are often set in various precious metals to enhance their visual appeal.

Their striking colours and unique designs make these gemstones a frequent choice for engagement rings.

Now that you know how these gems are used, let's review common mistakes to avoid when shopping for red gemstones.

Common Mistakes to Avoid

When shopping for red gemstones, it’s easy to make mistakes that can impact both the value and enjoyment of your purchase. One of the most common errors is confusing spinel with ruby, as both gemstones can appear nearly identical to the untrained eye. Since ruby generally commands a higher price, misidentification can lead to overpaying for a spinel or undervaluing a ruby. Another pitfall is overlooking a gemstone's treatment history—treated stones, such as heat-treated rubies, are often less valuable than their untreated counterparts. Additionally, buyers should be cautious of gemstones with excessive inclusions or visible damage, as these flaws can affect both the durability and beauty of the stone. By staying informed and asking the right questions, you can avoid these common mistakes and confidently choose the perfect red gemstone for your collection.

With these tips in mind, let's summarize why red gemstones like ruby and spinel are such cherished choices.

Why Choose a Red Gemstone

Red gemstones, especially ruby and spinel, are cherished for their striking beauty, rarity, and rich symbolism. Ruby, with its deep red colour and legendary status, is a classic choice for engagement rings and fine jewelry, representing love, passion, and commitment. Spinel, offering a vibrant red hue and exceptional brilliance, is an affordable alternative that doesn’t compromise on style or durability. Both gemstones are highly durable, making them ideal for everyday wear and ensuring your jewelry remains stunning for years to come. Whether you choose ruby for its prestige or spinel for its value and vibrant colour, both gemstones add a touch of sophistication and elegance to any jewelry collection. With their unique qualities and lasting appeal, ruby and spinel are perfect choices for anyone looking to make a statement with their jewelry.

In conclusion, understanding the differences between ruby and spinel gemstones involves examining their origins, colour characteristics, physical and chemical properties, clarity, market value, and symbolic significance. Both gemstones have unique appeal: rubies are more valuable, while spinels offer a more affordable yet equally beautiful alternative. These stunning gemstones continue to captivate and inspire, whether for investment or personal adornment.

Is the black Prince's ruby a stone called a spinel?

Yes, the Black Prince's Ruby is a red spinel, not a true ruby. It weighs 170 carats and is prominently featured in the Imperial State Crown of the United Kingdom.

Is spinel precious or semiprecious?

Spinel is traditionally classified as a semi-precious gem, but its beauty and increasing popularity elevate its status in the gem market. Its diverse colours and bright, vitreous lustre contribute to its appeal.

What are the primary colours of rubies and spinels?

Rubies are primarily vivid red, ranging from pinkish-red to deep blood-red, while spinels showcase a broader spectrum, including red, blue, pink, orange, and black.

How do the origins of rubies and spinels affect their value?

The origin of rubies greatly enhances their value, particularly with Burmese rubies being the most prized. Meanwhile, high-quality spinels free of visible inclusions also command a higher market price.

What are the typical inclusions found in rubies and spinels?

Rubies typically contain liquid inclusions like fingerprints and discoid fractures, whereas spinels may exhibit distinctive optical features such as pleochroism and two-phase inclusions. Understanding these features enhances appreciation for the uniqueness of these gemstones.