Difference Between Heated and Unheated Sapphire How It Affects Sapphire Value?

Posted on September 28th, 2023 05:32 PM

While you search for an sapphire engagement ring, you may see phrases such as "heated sapphire" and "unheated sapphire." The reason is in how the stones are treated and how they affect their value and rarity. Sapphires that have been heated are exposed to high temperatures to increase the clarity and color of their stones. This is a procedure that's typically applied to rocks of lower quality to improve their look. Sapphires that are not heated are natural Gems with no treatment that have become increasingly scarce. Beauty is always dependent on the eyes of the observer. No heat sapphire's biological roots significantly increase its value for buyers who know as well as collectors.

What Is Sapphire Heating?

Sapphire heating is a process where sapphires are exposed to high temperatures, typically over 1800°C, to alter their color and clarity. Unheated sapphires can lack saturation and appear too dark or inconsistent in color. Heating sapphires improve their appearance by enhancing and brightening their color as well as increasing their clarity.

Heating sapphires is a common practice and does not damage the stone or decrease its hardness. However, some consumers prefer unheated sapphires as they believe they are more natural and rare. These sapphires tend to be more valuable to collectors and gemstone investors.

When shopping for sapphires, you may come across descriptors like "natural unheated" or "heated". It is important to understand the difference to determine which stone best suits your needs and budget. If preserving the stone's natural state is most important, opt for an unheated blue sapphire. If color intensity is most important and budget is a concern, a heated sapphire can be a beautiful, affordable option.

heated and unheated blue sapphires

How Heating Affects a Sapphire’s Appearance

As an avid gemstone enthusiast, you likely appreciate the enticement of a vibrant blue sapphire. However, you may not realize that a sapphire’s captivating color can often be enhanced through a process known as heat treatment. This procedure involves exposing the sapphire to extremely high temperatures, which alters its molecular structure and produces more saturated hues.

While heat treatment is a common practice and does not necessarily reduce a sapphire's durability or quality, it can impact its value. In general, these sapphires tend to be more prized by collectors and gemologists. They believe that no heat stones better represent a sapphire's natural beauty and geological origins. Unheated sapphires also tend to exhibit a wider array of colors, from light blues to deep indigos.

Heated sapphires, on the other hand, typically display a uniform, intensely saturated blue color due to the heat treatment. This can give them an almost synthetic appearance. For this reason, heated sapphires are usually less valuable on the gemstone market, especially for rare, high-quality stones.

For the casual consumer in the market for an affordable sapphire ring or necklace, a heated stone may be perfectly suitable and still possess an enticing color. As with any gemstone purchase, the most important factors are that you appreciate its beauty and that it fits your budget.

In summary, while heat treatment may enhance a sapphire color, it often reduces its monetary worth. For gemstone investors, these sapphires will frequently prove the more precious of the two. However, for the average jewelry owner, either a heated or no-heat sapphire can make a stunning adornment and cherished gift. The choice comes down to your preferences regarding color and cost.

The Value of Unheated Sapphires

Unheated sapphires are prized for their natural beauty and scarcity. As sapphires are exposed to heat treatment, the crystal structure can be altered, and color intensified. For this reason, non-heated sapphires are considered extremely rare and valuable to collectors and gemologists.

Authenticity:- Unheated stones retain their original crystal structure and chemical composition. They represent sapphires as they are found in nature, untreated and unenhanced. For those seeking the rarest and most natural gemstones, nonheated stones are the pinnacle. Their colors have not been artificially enriched or intensified through heat exposure.

Vibrancy:- While heated these stones often exhibit very saturated and intense colors, these stones show a more comprehensive range of more natural tones. Their colors tend to appear softer and more muted. For some collectors, the subtler shades of unheated sapphires are more appealing. The biological origins of their colors are prized over intensity alone.

Rarity:- As sapphire heat treatment has become more widespread, unheated sapphires have become exceptionally rare. Sapphires with a combination of factors like large carat size, high clarity, and desirable natural color are scarce and even more unheated. This elevates their status and value for serious collectors.

Premium Value:- Due to their authenticity, natural beauty, and extreme rarity, nonheated sapphires command a premium price over heated sapphires. All other factors being equal, an unheated blue sapphire can be valued at up to 50% higher than a comparable heated sapphire. As more people discover the charm of all-natural gemstones, demand for these sapphires will likely continue to rise, elevating their position as one of the most prized colored gemstones.

For gemstone and jewelry aficionados seeking the finest and rarest, these sapphires represent the pinnacle of quality and beauty. Their natural origins and scarcity establish them as coveted gems for collections and heirloom pieces to pass down for generations. Though subtle in appearance, their allure is timeless.

blue sapphire gemstone

Identifying Heated vs. Unheated Sapphires

Identifying whether a sapphire has been heated or remains in its natural unheated state requires expert analysis. As an amateur, there are a few signs you can look for to determine if a sapphire may have been heated.

Color Saturation:- Heated sapphires often exhibit an unnaturally high color saturation, meaning the color appears intensely vivid and concentrated. These sapphires tend to have a more uneven, dusky coloration. If a sapphire hue seems unusually bright and saturated, it may indicate heat treatment.

Presence of Color Concentrations:- Unheated yellow sapphires typically have areas of uneven color, including lightly colored or colorless patches. Heating a sapphire distributes color evenly throughout the stone. Look for sapphires with a consistent, homogenous color throughout, with no lighter or colorless areas, which can signify heating.

Silk Inclusions:- Natural unheated sapphires frequently contain tiny needle-like inclusions known as silk. These inclusions typically appear whitish and clustered together. Heating a sapphire often dissolves silk inclusions, so their absence may suggest the stone has been heat treated.

Surface Pitting:- No heat sapphires can display small pits, cavities, or surface aberrations formed during natural crystallization. Heating smoothes out surface imperfections, so a sapphire with an unusually smooth, glossy surface may have been heat-treated.

Without advanced testing, determining whether a sapphire has been heated or remains unheated can be challenging. However, by carefully analyzing certain attributes like color, inclusions, and surface features, you may be able to identify signs that suggest a sapphire natural or treated state. When in doubt, consult a certified gemologist to evaluate the sapphire and determine if heat treatment was used to enhance the stone.

blue sapphire stone

Unheated Blue and Yellow Sapphires: Rare Natural Beauty

Unheated blue and yellow sapphires are rare gems that showcase the natural beauty hidden within the earth. As these precious stones have not been subjected to heat treatment, their colors and clarity remain untampered, allowing the vibrant hues and inclusions formed over millions of years to shine through.

No heat blue sapphires in particular are exceptionally scarce, as the heating process is commonly used to improve color in paler stones. Sapphires with a naturally saturated royal blue hue are therefore the most coveted. Likewise, the presence of inclusions in unheated sapphires provides insight into the stone's origins and history. Rather than being viewed as imperfections, inclusions add character and act as a hallmark of naturalness in No Heat sapphires.

For these reasons, unheated blue sapphires and unheated yellow sapphires are the most prized of all by gemstone experts and dedicated collectors. Although often more expensive, these stones are a sound investment, holding their value and appeal due to their rarity and irreplicable beauty. For those seeking sapphires in their purest essence, unheated sapphires showcase the wonder of nature at its finest. Their dazzling colors and internal mysteries have endured, untouched, for untold ages a glimpse into deep time through gems of unheated blue and yellow.


Choosing a heated or unheated sapphire ultimately depends on personal preference and budget. Sapphires offer intense, saturated colors at a lower cost. However, sapphires that are not heated are prominent because of their beautiful natural appearance as well as their rarity. Like any other gemstone one of the main elements is the fact that you like the stone, and you feel secure about your purchase. Do some research on sapphire treatments and origins to determine what aspects are most meaningful to you.


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