Shopping for sapphire can be daunting and overwhelming. The flood of synthetic and fake sapphires into the market in recent years has made the situation even more challenging. And even if you get a natural sapphire, there is still the question of whether it is an untreated and treated stone.

Advances in sapphire treatment technologies since the 2000s, such as the beryllium diffusion treatment, have significantly changed the dynamics and pricing of the sapphire market. Different types of sapphires can vary hugely in their values, which can range from less than $1 per carat for a glass filled composite sapphire to more than $20,000 per carat for a natural untreated, eye clean, vivid blue sapphire.

There are many different types of sapphires on the market: natural, real, synthetic, fake, untreated, treated, heated, unheated, and so on and so forth. How do you know you are not buying a fake sapphire? And what is a synthetic sapphire anyway? What about heated sapphire? How to make sure you are getting a good quality sapphire at a fair price? All these questions are confusing enough to give anyone a headache.

There are 4 main types of sapphires that any sapphire buyer should be aware of:

• Untreated Natural Sapphires: These are gemstones mined from the earth that have not gone through any artificial treatment. They are by far the rarest (less than 1 percent of the market) and the most valuable sapphires.
• Treated Natural Sapphires: These are also mined from the earth. But their colors and clarity were not good enough so they have gone through treatments to enhance their appearances. Different types of treatments are available. Some types of treated sapphires are worth very little while others can be quite valuable.
• Synthetic Sapphires: These are created in labs. They are still real sapphires but they are not natural.
• Imitation Sapphires: These are fake sapphires. They may look like sapphires but they are actually colored glass, cubic zirconia, or other substances. They are quite worthless.

In the next few sections, we will look at these different types of sapphires in detail. We will also show you the various ways to tell them apart. For those in a hurry, below is a table summarizing the information regarding these sapphire types and the methods to tell them apart.

Sapphires: Natural Untreated vs. Natural Treated vs. Synthetic vs. Imitation

Natural Sapphires

Natural sapphires are sapphires that were dug out of the ground. They formed slowly underground over many years in nature without any human intervention. Eventually, they got mined from the earth by humans and got cut and polished into the gemstones you see in stores.

Natural sapphire mines can be found in many different countries including Afghanistan, Australia, Myanmar/Burma, Cambodia, China, Colombia, India, Kenya, Laos, Madagascar, Malawi, Nepal, Nigeria, Pakistan, Sri Lanka, Tajikistan, Tanzania, Thailand, United States, and Vietnam. Not all sapphire mines are equal. Sapphires from certain locations are more appealing than others. Specifically, sapphires from Kashmir, Burma, or Sri Lanka are known worldwide for their high quality and vivid colors.

The world’s most expensive sapphires come from Kashmir, high up in the Himalayas. Due to the high altitude of their location, these sapphires can only be mined for a few months out of the year. Kashmir sapphires are special – they are known for their unique, soft, velvety colors.

Currently, the world record of the highest price per carat for a sapphire is being held by a Kashmir sapphire – it was sold for an astounding $242,000 per carat in 2015 at an auction in Hong Kong conducted by the auction house Sotheby’s.

Compared to synthetic and imitation sapphires, natural sapphires are typically more valuable. But even then, not all natural sapphires are equal. In general, there are 2 types of natural sapphires:

• Untreated natural sapphires
• Treated natural sapphires

Let’s take a look at them in detail

Untreated Natural Sapphires

Treatment/ Synthetic Process	No
Where Are They From?	Mined from the earth
Real Sapphires?	Yes
Natural Sapphires?	Yes
Rare?	Yes. Less than 1% of the market
Price Per Carat	$2,000 to $20,000+ Record is $242,000

Untreated natural sapphires are sapphires that have been mined from the earth and then cut and polished. Nothing else has been done to them. These are sapphires in their most natural and original state. Their color is vivid enough and their clarity is good enough that no artificial enhancements are needed.

Untreated sapphires are very rare. By some estimates, less than 1 percent of the natural sapphires on the market are untreated.

Untreated sapphires are also much more expensive than treated sapphires. Those sapphires you see setting price records at auctions? They are all untreated natural sapphires. And if you buy sapphires at a retail store, an untreated sapphire will also cost significantly more than a treated one.

Treated Natural Sapphires

Treatment/ Synthetic Process	Heat Only	Fissure Filling	Diffusion
Where Are They From?	Mined from the earth	Mined from the earth	Mined from the earth
Real Sapphires?	Yes	Yes	Yes
Natural Sapphires?	Yes	Yes	Yes
Rare?	No	No	No
Price Per Carat	$200 to $2,000+	Less than $1	$20 to $200

The vast majority (99 percent or more) of natural sapphires you can buy on the market are treated. These are sapphires that may not look very good without enhancements – their color is not quite deep enough, their clarity seems a bit cloudy, or there may even be cracks in them that need to be filled. When we say a sapphire is treated, we mean that it has undergone certain artificial processing (“treatment”) that typically aims to enhance its appearance such as its color and clarity.

There are 3 main types of treated sapphires:

• Heated (Heat Only) Sapphires
• Composite Sapphires (Glass Filled Sapphires)
• Diffusion Treated Sapphires

In the next 3 sections, we will look at these 3 types of treated sapphires one by one.

Heated (Heat Only) Sapphires

Heat treatment is the oldest and most common treatment for sapphires. When you buy a sapphire from a retailer, there is a good chance that it is a heated sapphire.

Some heat treatments are quite mild, in which sapphires are heated to a temperature of about 400 degrees Celsius for short periods of time. More recently, heat treatments involving much higher temperature and longer duration have been developed. In these treatments, sapphires are baked in furnaces in temperatures between 800 and 1,800 degrees Celsius for hours or even weeks at a time. This intensive heat treatment radically enhances the colors of sapphires to make them look more vivid and saturated. It also improves the clarity of the stones.

Heat sapphires that have gone through heat treatments without the use of any additives are sometimes called “heat only” sapphires.

Composite Sapphires (Glass Filled Sapphires)

Every year, large quantities of low quality natural sapphires are mined from the ground. These low grade sapphires are full of cavities, fractures, and fissures that compromise their clarity and make them unfit for use as gemstones.

Fissure filling is a treatment that will turn these low grade sapphires into salable gemstones. In this treatment, sapphires with fissures are heated with a chemical flux. At high temperatures, the flux melts and permeates the surfaces of these sapphires to fill up the cavities and fissures in these stones. When the sapphires cool, the chemical flux solidifies into a glass that masks the signs of fissures. In more extreme cases, poor quality sapphires on the verge of breaking apart are being held together by the glassy filler.

Sapphires that have gone through this fissure filling treatment are referred to as “composite sapphires.”

Diffusion Treated Sapphires

Diffusion treatment is a relatively new treatment. In this treatment, sapphires are heated to almost their melting point in the presence of color-inducing elements such as titanium or beryllium. The goal is to enhance the sapphires to give them a saturated vivid color.

In the case of titanium, under high heat it will diffuse onto the surface of sapphires to form a very thin (less than 0.5 mm) layer of vivid blue color. In the case of beryllium, it will penetrate deep into the crystal lattice of sapphires due to the small size of beryllium ions. This creates a color layer that is much harder to detect than that created by titanium diffusion. In some cases, the artificial color penetrates the entire stone. Initially, orange sapphires were created by beryllium diffusion. The process has since been advanced to the point where many different colored sapphires can be created by this treatment.

How to Tell Untreated & Treated Sapphires Apart

As mentioned, untreated natural sapphires are significantly more valuable than treated ones. You do not want to pay the untreated price for a treated sapphire. So how do you tell them apart?

One of the best ways to differentiate treated sapphires from untreated ones is by observing their inclusions. An inclusion is any material that is trapped inside a crystal during its formation. The inclusions in a sapphire can be other minerals, rocks, water, gas bubbles, or petroleum.

Untreated natural sapphires have a few characteristic inclusions. It turns out various treatments will leave behind their own unique inclusions. By observing a sapphire under a microscope, it is possible to use these inclusions as evidence to determine whether the stone has been treated or not:

• Untreated Natural Sapphires: The best natural sapphires are “Eye Clean”,” that is, they do not have visible inclusions when examined by the naked eyes 10 to 12 inches away. However, almost all natural sapphires have visible inclusions when examined using a microscope. The most common untreated sapphire inclusions are rutile needles (silk), feathers, crystal, and fingerprints.
• Heated (Heat Only) Sapphires: The heating process can easily damage the rutile needles in untreated sapphires. So look for broken silk or partially “reabsorbed” rutile needles. Another telltale sign is melted or “rounded” crystal inclusions.
• Composite Sapphires: A composite sapphire shows intersecting, criss crossing lines throughout the stones under a microscope. These lines are the fissures that have been filled by the melted glass. There likely will also be air bubbles in the glass filler.
• Diffusion Treated Sapphires: Diffusion treated sapphires can be very difficult to identify. Look for blue halo inclusions in the stone – they are a characteristic sign of diffusion treatment that is not present in untreated sapphires.

All these telltale signs are subtle and microscopic. Unless you are a trained gemologist, you will probably not be able to pick them out. In reality, as a sapphire buyer, your best bet is to buy from reputable sellers only.

Also, ask to see a gemstone certificate before you hand over your money. For more expensive purchases you might also want to get an independent lab to test and certify the sapphires before you complete the transaction.

When it comes to testing and certifying sapphires, stick with the most reputable labs. Any company from the following list would be a good choice:

• GIA – Gemological Institute Of America
• AGS – American Gem Society
• GCAL – Gem Certification & Assurance Lab
• IGI – International Gemological Institute
• EGL – European Gemological Laboratories

Synthetic (Lab Grown) Sapphires

Treatment/ Synthetic Process	Verneuil Process	Czochralski Process	Hydro-thermal Synthesis
Where Are They From?	Made in lab	Made in lab	Made in lab
Real Sapphires?	Yes	Yes	Yes
Natural Sapphires?	No	No	No
Rare?	No	No	No
Price Per Carat	$1 to $5	$10 to $50	$100 to $200

Synthetic (or lab grown) sapphires are sapphires that are created (or grown) in a lab. They are real sapphires in every sense of the word. When compared to natural sapphires, synthetic sapphires have the exact same chemical compositions and physical properties. That is why synthetic sapphires are real sapphires. There is nothing “fake” about them.

Synthetic sapphires tend to be less expensive than natural sapphires of similar quality because synthetic sapphires are more plentiful and can be mass produced in a controlled environment. As a result of this precise, engineered production method, synthetic sapphires are also typically more uniform, more perfect, more vivid in color, and have fewer inclusions.

Natural sapphires, on the other hand, are formed slowly over eons in the chaotic and unpredictable environment of nature. That chaotic environment means that many things could go wrong during the formation of natural sapphires. As a result, natural sapphires are usually less perfect, less vivid in color, and have more inclusions.

When it comes to the question of which type of sapphire – natural or synthetic – is better, it really comes down to personal preference and economic considerations.

As we have mentioned, synthetic sapphires are cheaper. Hence, if you are on a tight budget, synthetics are probably the way to go for you.

In the cases where budget is not a concern, most people prefer natural sapphires, mainly because of the rarity factor. Natural sapphires are rarer and more valuable. That makes them more prized and sought after.

On the other hand, some people actually prefer synthetic sapphires for environmental and sustainability reasons. Natural sapphires need to be mined from the earth. The act of mining itself can cause a lot of damages to the environment. In comparison, growing synthetic sapphires in a lab is a much more sustainable way to produce sapphires.

There are 2 main types of methods for producing synthetic sapphires: melt processes and solution processes. Melt processes involve melting aluminum oxide into a sapphire droplet. Solution processes involve growing sapphire crystals in a solution. Let’s take a look at them in more detail.

Synthetic Sapphire Production Methods – Melt Processes

In melt processes, aluminum oxide (the principal mineral in corundum) is melted into a sapphire droplet. Among the various melt processes, the oldest and most inexpensive one is known as flame fusion, or the Verneuil process. It was invented by the French chemist Auguste Verneuil in 1909.

In flame fusion, aluminum oxide (corundum) powder is being melted by a flame. The corundum drops form into a long teardrop shape known as a “boule.” The addition of trace amounts of other minerals to the aluminum oxide will produce sapphires in various colors.

On the plus side, the Verneuil process can produce sapphires that are much bigger than those usually found in nature. On the minus side, sapphires produced by this process typically have high internal strains, resulting in gemstones that are brittle and easy to break.

Another common melt process is the Czochralski process, which was invented in 1916 by the Polish chemist Jan Czochralski. In this process, aluminum oxide is melted by radio waves. A rod tipped with a tiny seed sapphire crystal is inserted into a crucible containing the melting aluminum oxide. The crucible itself is made of the precious metal iridium or molybdenum. The rod is then slowly rotated and pulled out at a rate of 1 to 100 mm per hour. As a result, a long carrot-shaped boule of sapphire crystal is created.

While the Czochralski process is an expensive way to produce synthetic sapphires, it is a speedy way. It can produce up to 4 inches of sapphire crystal per hour.

Synthetic Sapphire Production Methods – Solution Processes

In solution processes, sapphires crystals are being grown in a solution. One of the most popular solution processes of growing sapphire is known as hydrothermal synthesis.

Hydrothermal synthesis is a type of solution process that closely mimics the process in which natural sapphires are formed in nature. In this process, a sapphire crystal is grown inside a steel pressure vessel called an autoclave, which is like an industrial “pressure cooker.” Aluminum oxide solution is subjected to intense heat and pressure inside this pressure cooker. A seed sapphire crystal is placed in this solution. Crystal grows around this seed to form the resultant sapphire. Trace amounts of elements such as iron and titanium are added to the aluminum oxide solution to make sapphires of various colors.

Hydrothermal synthesis is particularly suitable for the growth of large good-quality sapphire crystals while maintaining control over their composition. On the downside, this process requires autoclave which is an expensive piece of equipment. Sapphires grown this way is even more expensive than those made by the Czochralski process.

How to Tell Synthetic & Natural Sapphires Apart

Even though synthetic sapphires are real sapphires just like natural sapphires are, it is still important to be able to tell the 2 types of sapphires apart. Why? For one thing, if you prefer natural sapphires (and most people do) you would not want to buy a sapphire without making sure it is indeed natural. For another, even if you do not mind getting a synthetic sapphire, you would still want to know that the sapphires you are buying are synthetic. That way you will only pay the synthetic sapphire price for it. The last thing you want is to be conned into paying a natural sapphire price for a synthetic sapphire as natural sapphires are typically much more expensive than synthetics.

Because synthetic sapphires are real sapphires with the same chemical compositions and physical properties as natural sapphires, telling the two types of sapphires apart can be challenging even for experts.

Fortunately, by examining a sapphire with a binocular microscope, a skilled gemologist can identify little telltale signs that distinguish a natural sapphire from a synthetic one. In general, there are 2 types of telltale signs we can rely on to tell natural and synthetic sapphires apart:

• Growth Lines: These are subtle lines in gemstones caused by slight variations in the optical properties of the growing crystal. Growth lines mark different stages of the crystal growth.
• Inclusions: an inclusion is any material that is trapped inside a crystal during its formation. The inclusions in a gemstone can be other minerals, rocks, water, gas bubbles, or petroleum.

Natural sapphires have growth lines and inclusions that are subtly different from those of synthetic sapphires. Synthetic sapphires made with different production processes also come with different types of growth lines and inclusions. Let’s take a look at them one by one:

• Natural Sapphires: Natural sapphires have angular growth lines emanating from a single point and following the planar crystal faces. When it comes to inclusions, the most common natural sapphire inclusions are rutile needles (silk), feathers, crystal, and fingerprints. These inclusions are not found in synthetic sapphires
• Synthetic sapphires made with the Verneuil process (flame fusion): Synthetic sapphires created by this method have curved growth lines and curved color bands not found in nature.
• Synthetic sapphires made with the Czochralski process: Synthetic sapphires created by this method typically have inclusions such as gas bubbles and smoky veils that are not found in natural sapphires.
• Synthetic sapphires made with hydrothermal synthesis: Synthetic sapphires created by this method usually have distinctive inclusions that look a bit like nail heads. These inclusions are not found in natural sapphires.

All these evidences are very subtle and will be hard for a layperson to detect. As we have stated, your best bet as a buyer is to buy from reputable retailers only. Also, make sure you get a gemstone certificate from one of the major independent gemology labs.

Imitation Sapphires

Treatment/ Synthetic Process	Various
Where Are They From?	Made in lab
Real Sapphires?	No
Natural Sapphires?	No
Rare?	No
Price Per Carat	Less than $1

Unlike synthetic sapphires which are real sapphires, imitation sapphires are not sapphires at all. They are stones that look very much like sapphire but are in reality entirely different substances. They are typically much cheaper than both natural and synthetic sapphires.

Common substances that are used as imitation sapphires include blue colored glass and cubic zirconia. Needless to say, you do not want to be getting a cubic zirconia pretending to be a sapphire while paying the price of a real sapphire.

How to Tell Imitation and Real Sapphires Apart

There are a few methods you can use to tell real and fake sapphires apart.

• The Scratch Test: Sapphire is very hard, having a hardness rating of 9 on the Mohs scale. It is the 3^rd hardest natural mineral in the world, behind only diamond at 10 and moissanite at 9.5. Given its exceptional hardness, sapphire is extremely scratch resistant. If a sapphire has scratches or marks on its surface, it is very likely fake. You can also try scratching a sapphire with a coin or a key. If that leaves scratch marks on its surface, it is fake. A real sapphire will not be damaged by scratches in this way.
• The Breath Test: Sapphire is also a very good conductor of heat, significantly better than common fake sapphire materials such as glass or cubic zirconia. You can use this property to test for fake sapphires. Take a sapphire and breathe on it until it is completely fogged up. Count how long it takes for the fog to clear. For a real sapphire, the fog will disappear in just 1 or 2 seconds. For a fake sapphire, it will take about 5 seconds or more.
• Inclusions: Examine the sapphire using a binocular microscope. Real sapphires and sake sapphires have different types of inclusions. Inclusions in real sapphires include rutile needles (silk), feathers, crystal, fingerprints, smoky veils, and nail heads. Fake sapphires made from glass typically have air bubble inclusions. Fake sapphires that are cubic zirconia are typically flawless with no inclusions, although some may contain inclusions of small gas bubbles or zirconium oxide.