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How to Identify Rough Sapphire: A Comprehensive Guide

How to Identify Rough Sapphire

Have you ever stumbled upon a beautiful blue gemstone and wondered if it could be sapphire? Sapphire is a precious gemstone that belongs to the corundum mineral family.

It’s known for its vivid blue color, although it’s also found in other colors such as pink, yellow, and green. However, not all blue gemstones are sapphire, and not all sapphires are of high quality.

In this article, we’ll discuss how to identify rough sapphire using several methods.

Properties of Sapphire

Sapphire has several unique properties that set it apart from other blue gemstones. First, sapphire is one of the hardest minerals, coming in a 9 out of 10 on the Mohs scale of mineral hardness.

This means that it’s unlikely to have scratches or abrasions on the surface. Second, sapphire has a high refractive index, which means that light bends as it passes through the gemstone, creating a brilliant sparkle.

Finally, sapphire is very dense, giving it a weight that feels more substantial than other gemstones of a similar size.

Using a Loupe

One of the most reliable ways to identify sapphire is by using a jeweler’s loupe or magnifying glass. Look for any bubbles or inclusions within the stone.

Bubbles may indicate that the stone is glass or a synthetic material, while inclusions can help determine if it’s indeed sapphire. Inclusions within sapphire can often resemble fingerprints, needles, or crystals.

However, sapphire can also contain silk, which are tiny needle-like inclusions that can create a silky appearance when viewed under the light.

Testing Streak and Hardness

Another way to identify sapphire is by testing its hardness. You can use a piece of quartz or topaz to scratch the surface of the stone.

Both quartz and topaz are harder than sapphire and will leave a colorless streak if the stone is indeed sapphire. However, it’s important to note that if the stone has been cut or polished, this method may not work, so it’s important to use it in conjunction with other methods.

Testing Specific Gravity

Testing the specific gravity of a stone can help determine if it’s sapphire. Specific gravity is the ratio of a mineral’s density to the density of water.

You can measure specific gravity by weighing the stone first in the air and then in water. Divide the weight in air by the weight in water, and you’ll get the specific gravity of the stone.

Sapphire has a specific gravity of approximately 4.00, which means that it’s much denser than a stone that floats in water.

Identifying Sapphire Inclusions

Inclusions are tiny imperfections within a gemstone that are formed during the stone’s growth process. While inclusions can sometimes lower a stone’s value, they can also provide valuable insight into the stone’s origin and can even be used to authenticate its natural state.

Common Inclusions in Sapphire

Sapphires can contain several types of inclusions, including feathers, needles, fingerprints, crystals, and halos. Feather inclusions are tiny fractures that can sometimes create a white haze within the stone.

Needle-like inclusions resemble tiny sticks and are often seen in sapphires of lower quality. Fingerprints appear as shapeless or round inclusions and form when the stone is still in its growth process.

Crystals can sometimes appear as hexagonal shapes, and halos are circular inclusions that appear like rings within the stone.

Significance of Inclusions

One of the most significant aspects of inclusions in sapphires is that they are natural and unique to each stone. Inclusions can sometimes indicate the geographic location or conditions that the stone was formed in.

However, inclusions can also affect the stone’s value and can sometimes make it less desirable to buyers. Heat treatment, a common practice in the gemstone industry, can remove or alter inclusions in sapphires, making it difficult to determine the stone’s natural state without proper certification.

Importance for Gemologists

For gemologists, identifying sapphire inclusions is essential for determining the stone’s value and quality. A trained gemologist can use the presence or absence of certain inclusions to authenticate the stone’s natural state.

Certification by a reputable gem lab is often recommended and is essential to establish the value of a sapphire for collectors and buyers.


Sapphire is a beautiful and precious gemstone that is sought after for its vivid blue color and high durability. Whether you’re a gemstone enthusiast or shopping for engagement rings, knowing how to identify sapphire is essential.

By using jeweler’s loupes, hardness tests, specific gravity tests, and identifying inclusions, you can tell if the blue stone you’ve found is a genuine sapphire. As with all precious stones, it’s important to authenticate your purchase by seeking certification from a reputable gem lab to ensure your investment is authentic and valuable.

Additional Steps for Successful Identification of Sapphire

Identifying sapphire gemstones can seem like a daunting task, especially with the variety of shapes and colors in which they appear. However, several important steps can aid you in accurately identifying the stone’s type and value.

While we’ve already discussed several methods of identifying sapphire, there are additional steps you can take to ensure a successful identification.

Research and Provenance

One of the most critical steps before identifying sapphire is doing thorough research about the stone’s origin and history. Understanding the source of the gemstone can provide valuable insights into its authenticity, quality, and value.

For example, sapphires sourced from Sri Lanka and Kashmir are generally of higher quality and are more valuable than those sourced from other locations. In addition to research, identifying sapphire can also involve analyzing its provenance or history.

A stone with a well-documented history that dates back several years or even decades is more likely to be authentic than one with vague origins.

Fakes and Dyeing

Unfortunately, sapphires are not exempt from the world of imitation and fake gemstones. Imitations, such as glass, plastic, or synthetic corundum, can be sold as sapphire, and it’s easy to mistake them for the genuine article.

One way to avoid this is by carefully inspecting the stone’s color, clarity, and durability. Additionally, bubbles or unevenness in the color can indicate an imitation.

Dyeing is another practice used to enhance a stone’s color or mask inclusions. Dyeing can be challenging to detect with the naked eye, but experienced gemologists can expose them using specialized equipment.

Prices for dyed sapphires are generally lower than untreated ones.

Professional Testing

Professional testing by certified gemologists is often the best way to assure identification results. Gemological assessment by reputable labs provides a scientific analysis of the stone and provides certification of the gemstone’s value.

While professional testing can be costly, it’s highly recommended for valuable gemstones and investment purposes.

Conclusion and Recommendations

Identifying sapphire gemstones requires attention to detail and careful consideration. While there are multiple methods to test sapphires, utilizing the right approach is key to an accurate identification.

Swiftly identifying a gemstone can save time, money, and heartache in the long run.

Final Thoughts and Summary

In summary, sapphires are a valued and sought-after gemstone. Several prominent characteristics define sapphires, including color, clarity, and durability.

Specific steps that include visual analysis through proper magnification, assessing streaks, hardness tests and specific gravity, identifying unique inclusions, and doing research are a few key steps to ensuring an accurate identification process.

Recommendations for Identification

When identifying sapphires, it’s important to be attentive to key characteristics such as origin and period of the stone’s extraction. Although it can be challenging to distinguish between genuine and synthetic sapphires, paying attention to small details in the stone’s appearance can make a significant difference.

Professional testing and certification are recommended for high-end purchases and investments. Working with highly respected sources and certified gemologists can help build confidence in your identification results.

In conclusion, sapphire identification is both exciting and essential for appraisal, investment, and the art of collecting these stunning gemstones. By familiarizing yourself with the necessary identification techniques, being diligent in stone inspection, and leveraging certified resources, you can spot imitations and appreciate the rare beauty of genuine, high-quality sapphires.

In conclusion, identifying rough sapphire gemstones requires a careful examination of the stone’s properties, inclusions, and unique characteristics, as well as proper research and provenance. Testing for sapphire involves using the right approaches, including magnification, hardness tests, and specific gravity.

Finally, obtaining professional certification from reputable gemological labs is recommended for high-value investments. By enlisting these steps in sapphire identification, it becomes easy to determine the stone’s quality, value, and origin.


1) What are the properties of sapphire that set it apart from other gemstones? – Sapphire is one of the hardest minerals, has a high refractive index, and is very dense.

2) Can inclusions provide insight into a sapphire’s origin and authenticity? – Yes, inclusions can indicate the geographic location or conditions that the stone was formed in and can authenticate its natural state.

3) How can I distinguish genuine sapphire from fake gemstones? – By carefully inspecting the stone’s color, clarity, and durability, and looking for bubbles or unevenness in color that can indicate an imitation.

4) Is professional testing necessary for identifying sapphire? – Professional testing and certification by reputable gemological labs are recommended for high-value investments.

5) Why is research and provenance important in sapphire identification? – Understanding the stone’s origin and history provides valuable insights into its authenticity, quality, and value.

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