How Can You Tell If A Black Sapphire Is Real?

By | October 18, 2023

How Can You Tell If A Black Sapphire Is Real?

How Can You Tell If A Black Sapphire Is Real? Black sapphires are coveted gems that exude a striking elegance, but how can you determine if the one you’ve come across is the real deal? With their mysterious allure and deep black hue, these gemstones can sometimes be difficult to authenticate. Fortunately, there are a few telltale signs that can help you determine the authenticity of a black sapphire. From examining its color consistency to assessing its clarity and refractive properties, this article will guide you through the process of discerning the authenticity of a black sapphire, ensuring that your precious gem is truly the genuine article.

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Visual Inspection

When visually inspecting a black sapphire, there are several characteristics to consider. The first is color. A genuine black sapphire will display a deep, rich black hue. It should be consistent throughout the entire stone, without any noticeable variations or inclusions that could indicate it is synthetic or treated.

Next, consider the clarity of the sapphire. Natural black sapphires may contain some inclusions, but they should not be overly visible to the naked eye. Clarity can greatly affect the value of a black sapphire, so it is important to carefully examine the stone for any prominent flaws or blemishes.

Lastly, transparency is key when evaluating a black sapphire. A genuine stone will have a high level of transparency, allowing light to pass through and create a brilliant shine. If the stone appears hazy or lacks transparency, it may be an indication that it is not a real black sapphire.

Physical Properties

Two important physical properties to consider when determining the authenticity of a black sapphire are hardness and density. Black sapphires are a variety of the mineral corundum, which is one of the hardest minerals known to man. As such, a genuine black sapphire will have a high level of hardness and should not be easily scratched.

Density can also be indicative of a black sapphire’s authenticity. Sapphires have a higher density compared to most imitations or synthetic versions. By comparing the weight of the stone to its size, you can get a rough estimate of its density. Genuine black sapphires will generally have a greater density than most imitations.

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Refractive Index

The refractive index refers to how light bends as it enters and exits a gemstone. This property can be helpful in identifying a real black sapphire. Single refraction occurs when light enters a stone and bends in a single direction, resulting in a single image. Genuine black sapphires exhibit single refraction.

Double refraction, on the other hand, occurs when light enters a stone and splits into two rays, resulting in a double image. Black sapphires do not typically display this property. By examining the stone under magnification and observing how light behaves, you can determine whether the sapphire is real based on its refractive index.

Heating Test

Natural black sapphires are often subjected to heat treatment to enhance their color and clarity. While this treatment is commonly accepted in the gemstone industry, it is still important to be aware of. Heating a genuine black sapphire will not significantly change its appearance, whereas synthetic sapphires may display noticeable changes in color or clarity when heated.

Loupe Examination

Using a jeweler’s loupe to closely examine a black sapphire can reveal important information about its authenticity. Inclusions, or internal flaws, can provide valuable clues. Natural black sapphires may have some inclusions, but they should be consistent with those typically found in corundum. Synthetic sapphires, on the other hand, may exhibit different types of inclusions or have an absence of them altogether.

Growth patterns can also provide insight into a black sapphire’s authenticity. Natural sapphires often display characteristic growth patterns, such as angular or hexagonal shapes, indicating their natural formation. Synthetic sapphires, on the other hand, may show more uniform growth patterns or lack them entirely.

UV Light Test

Another test that can be performed is the UV light test. Genuine black sapphires may exhibit fluorescence under ultraviolet (UV) light. This means that when exposed to UV light, the stone may emit a glowing or fluorescent effect. However, not all black sapphires will fluoresce, so the absence of fluorescence does not necessarily indicate that the stone is not genuine.

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A spectrometer can provide further insights into the authenticity of a black sapphire. By analyzing the stone’s absorption spectrum, specific absorption bands can be observed. These absorption bands are unique to genuine black sapphires and can serve as a reliable indicator of their authenticity.


Examining a black sapphire under magnification can reveal important details about its faceting, polish, and symmetry. Genuine black sapphires will typically exhibit precise and well-executed faceting, with clean, crisp edges and facets. The polish should be smooth and even, with no visible scratches or irregularities. Additionally, the symmetry of the stone should be symmetrical, with all facets well-aligned.

Specific Gravity Test

Determining the specific gravity of a black sapphire can help in verifying its authenticity. Specific gravity is the ratio of the density of a substance to the density of water. By weighing the stone and comparing it to its volume, the specific gravity can be calculated. Natural black sapphires generally have a specific gravity higher than most imitations or synthetic versions.

Expert Certification

For a definitive confirmation of a black sapphire’s authenticity, it is recommended to seek expert certification. Gemological laboratories specialize in identifying and grading gemstones, including black sapphires. They can conduct a thorough examination using advanced equipment and techniques to confirm the stone’s authenticity. Additionally, appraisal services can provide detailed reports on the quality, value, and authenticity of a black sapphire, providing you with peace of mind in your purchase.

In conclusion, determining the authenticity of a black sapphire requires careful examination of its visual characteristics, physical properties, and various tests. By considering factors such as color, clarity, transparency, hardness, density, refractive index, loupe examination, UV light test, ultraviolet spectrum, magnification, specific gravity, and seeking expert certification, you can confidently identify whether a black sapphire is real or not. Remember to consult with reputable jewelers or gemological experts for the most accurate assessment of your black sapphire.

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Author: marklsmithms1

Hi, I'm Mark, the author of Maura Gems and Jewellery. As a team of qualified gemmologists and goldsmiths, we bring you world-class jewellery at Bangkok prices. With offices in both Bangkok and the UK, we ethically source the finest gemstones directly, eliminating any middlemen. We offer a wide range of stunning ready-made jewellery items in our new online store, available for retail or wholesale. Additionally, we specialize in custom-made jewellery where we can bring any design to life. Whether you're a trade professional or an individual customer, we cater to all. Feel free to email me at or call/WhatsApp me at 07470547636 or +66949355718. Discover our incredible collection by visiting our online store. I guarantee you'll love what you find there!

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