Is A Ruby A Red Sapphire? (Here’s The Truth)

Rubies and sapphires have much in common; they’re both gem-quality stones with a beautiful sparkle, ideal for jewelry. Not only that, but they have the same Mohs hardness of 9 and similar chemical makeup. So, then, is a ruby red sapphire?

Rubies are not red sapphires, but both gemstones are varieties of corundum. This mineral is an aluminum oxide crystal that appears in several colors depending on its impurities. When corundum has chromium traces, it becomes red – ruby. Yet, when it is another color, it is sapphire instead.

Now that we grasp the difference between ruby and sapphire, the rest of this post will examine why that’s the case. Read on to learn why corundum has these different varieties and which is best for you.

How To Define Ruby And Sapphire

Although rubies and sapphires are both forms of the corundum mineral, they have different names. That’s because of their color.

Ancient people didn’t know about chemistry and geology, so they couldn’t tell that ruby and sapphire were different varieties of corundum. Instead, they assumed that these minerals were largely distinct.

Because of that, red corundum earned a unique name – ruby. This word comes from the Latin’ rubrum’, meaning red. Its blood-red color was so striking that it needed this particular title.

Meanwhile, other corundum gems became sapphires. That’s true for all non-red corundum varieties, not just blue. Yellow, white, and black corundum are all sapphires, for example.

However, the word ‘sapphire’ refers only to the blue gem since it has historically been the most popular type. And that’s no surprise; the violet-blue hue is particularly gorgeous, even compared to other beautiful gems.

The name comes from the Latin’ saphirus’, which also means blue.

So, when discussing other corundum types, we mention the color alongside the name. For instance, I might own a yellow sapphire ring or a green sapphire broach. But if I had a blue corundum gem, I would call that sapphire.

What About Pink Sapphires?

There is no universal standard on what corundum counts as ruby and what does not. While everyone agrees that red corundum is ruby, some cases still toe the line, like pink.

Certain corundum varieties are pink, but does that make them rubies? Complicating this question is that people can’t agree on where pink ends or begins, either. Historically, pink wasn’t a different color from red. Therefore, pink sapphires would’ve been rubies.

However, in the modern day, pink counts as a different color.

And, since that color isn’t red, gemologists often categorize pink sapphires separately from rubies. That’s the official stance of the Gemological Institute of America.

Nevertheless, other groups, like the International Colored Gemstone Association, don’t differentiate between pink and red. Instead, they believe that any red corundum is a ruby, regardless of its color’s intensity.

What Is Fancy Sapphire?

Fancy sapphire is a term that gemologists use to discuss sapphires that aren’t blue.

These corundum types are far rarer than their blue counterparts, so they’re fancier. Nevertheless, they are still sapphires, albeit with different impurities.

However, pink-orange fancy sapphire also has a unique name. We call this gemstone padparadscha, which means ‘Lotus flower’ in Sinhalese, a Sri Lankan language.

Padparadschas are some of the rarest sapphire types, fancy or otherwise. Their unique salmon color range is striking even compared to other gem-quality stones. We have their chromium impurities to thank for the pink and iron for the yellow tones.

So, if you’re looking for a genuinely remarkable piece of jewelry, consider that lovely gemstone.

Why Do Impurities Change Corundum’s Color?

Pure corundum, or aluminum oxide, has the chemical formula Al₂O_3, and, in this state, it’s colorless – we call that white sapphire.

Also, pure Al₂O₃ has a uniform structure, with six oxygen atoms surrounding every aluminum atom. This shape makes an octahedron that doesn’t absorb any light. So, the crystal stays transparent.

It’s with the introduction of trace amounts of other minerals that the corundum will change color. Even though these chemicals are responsible for the rock’s magnificent color change, we call them impurities.

Impurities change corundum’s color by impacting the arrangement of its atoms. Suppose we replace one of the aluminum atoms with a chromium one. In that case, we disrupt the crystal’s careful balance of atoms and electrons.

Generic corundum has atoms with complete orbital levels, meaning there aren’t any free electrons that can interact with light. However, that’s not true for the impure varieties.

Those types can have spare electrons – or empty orbitals – that absorb light. So, that one chromium atom enables corundum to intake red light.

By doing so, the gemstone becomes red. Our chromium has become a ruby.

A similar principle applies to sapphires, but the impurities are different. Only chromium can cause corundum to become ruby. We’ll need other elements if we want another color, like blue.

If the corundum has iron, copper, or magnesium traces, its crystalline structure will also be slightly different. But instead of turning red, it’ll be blue thanks to these elements. Those atoms interact with light differently, letting the crystal absorb different wavelengths – different colors.

Can Rubies And Sapphires Change Color?

Jewelers can treat corundum to change its color. While nobody can turn a ruby into a blue sapphire, there are treatments to make dull stones brighter and more vivid.

The first way is heat treatment. By heating sapphires and rubies, jewelers can alter the intensity of their color. For instance, they could heat a pink sapphire until it darkens into a blood-red ruby.

Not only that, but heat treatment can also remove inclusions, making a gemstone clearer. Because of this invention, we have far more sapphires available. Jewelers can heat what were previously unusable rocks into gem-quality stones.

The second is lattice diffusion. This technique allows foreign atoms to enter a crystal while it undergoes heat treatment.

As we saw above, atomic impurities change corundum’s color. So, by introducing new atoms into a sapphire’s crystal lattice, we can change what light it absorbs. However, because this treatment necessitates profound changes, jewelers must disclose if they’ve used lattice diffusion on a gem. Because that stone isn’t natural anymore, it’s worth less.

Last, there’s irradiation. By exposing a mineral to irradiation, we can change its color. Although we can get drastic changes with this method, they aren’t permanent. Irradiated sapphires can fade, especially under intense light.

Conclusion

To sum this topic up, rubies are not red sapphires. Instead, sapphires and rubies are two different corundum mineral types, which change color depending on their impurities.