Rubies are one of the most coveted gemstones, renowned for their stunning red hue and rarity. For both jewelry lovers and investors, testing a ruby’s authenticity and quality is essential before making a purchase. While professional gemological testing is the most accurate, there are several methods you can use at home to determine whether a ruby is genuine. This guide will explore various home testing techniques, from simple visual inspection to more advanced methods.
Background of Ruby Gemstones
Rubies are a variety of corundum, just like sapphires, but are distinguished by their red color. The red is primarily caused by the presence of chromium within the crystal structure. Rubies are among the rarest and most valuable gemstones, particularly those with a deep red color, known as “pigeon blood.” Rubies are found in various locations around the world, including Myanmar, Thailand, and Sri Lanka. They are highly prized for their beauty, durability (second only to diamonds), and significance in various cultures.
However, the high value of rubies also means they are often imitated or altered. It is important for anyone purchasing rubies, especially from online or second-hand sources, to verify the authenticity of the gemstone.
1.Visual Inspection: The First Step in Ruby Testing
The most straightforward way to test whether a ruby is genuine is through visual inspection. A trained eye can often spot the difference between a real ruby and a synthetic or imitation stone. Here are a few methods to try:
Color Examination
Genuine rubies have a deep, rich red color, often with hints of purple or orange. The most sought-after rubies have a vivid, “pigeon blood” red hue. When inspecting a ruby, consider:
- Color Intensity: A genuine ruby will have a vibrant color, with no dull or washed-out areas. Rubies with uniform color are often high quality, though inclusions may cause slight variations.
- Transparency: While rubies can have inclusions, they should still maintain a certain level of transparency. A ruby that appears opaque may be a synthetic gemstone.
Inclusions (The Natural Signature)
Rubies naturally contain inclusions, also called “fingerprints,” which can help distinguish them from synthetics. A trained gemologist can often spot these inclusions under magnification, but a basic home test can be done with a jeweler’s loupe (10x magnification).
- Natural vs. Synthetic Inclusions: Inclusions in natural rubies tend to be irregular and asymmetrical, while synthetic rubies often have more uniform or even patterns.
- “Silk” Inclusions: These are needle-like inclusions of rutile found in many rubies and are one of the key signs of natural rubies. Synthetic rubies often lack these inclusions or have fewer of them.
Surface Examination
Inspect the surface of the ruby for scratches or imperfections. While rubies are extremely durable, they can still develop surface wear. Synthetic rubies might have a glassy or too-perfect appearance with little to no imperfections on the surface. Natural rubies will often have slight imperfections, including chips, scratches, or surface scuffs.
2. The Heat and Flame Test
A well-known test for many gemstones, the heat test can be performed on rubies as well. However, it is important to proceed with caution, as overheating a ruby can damage it.
Heat Resistance
Rubies are one of the most heat-resistant gemstones, with a melting point of over 2,000°C. If you hold a ruby near a flame for a few seconds, a genuine ruby will show no change in color or shape. Synthetic rubies, especially those made from glass or other low-melting materials, may crack or change color when exposed to heat.
Applying the Heat Test
To conduct a simple heat test, use a pair of tweezers to hold the ruby and briefly expose it to a flame. After removing it, examine the ruby for any changes, such as discoloration or cracking. Keep in mind, this test should only be performed if you are certain the ruby is not fragile or treated with heat-sensitive materials.
3.The Water Test
This test is simple and can be done with a glass of water. The way a ruby interacts with water can give clues to its authenticity.
Refraction Test
Rubies have a high refractive index, meaning they bend light significantly. Drop the ruby into a clear glass of water and observe how it reflects light. A real ruby will cause sharp, bright reflections and light dispersion. Imitation stones, such as glass or plastic, may not have the same reflective qualities.
Specific Gravity Test
The specific gravity of rubies is around 4.00, which means they are relatively heavy for their size. If you have access to a scale, you can weigh the ruby in air and water to calculate its density. The difference in weight between air and water should correspond to a specific gravity of approximately 4.00 for a genuine ruby.
4. The Scratch Test: Testing Hardness
Rubies are one of the hardest natural gemstones, rated 9 on the Mohs scale of hardness. This makes them highly resistant to scratching by most substances, except for diamonds.
Scratch Resistance
Try gently scratching the ruby with a known material, such as a piece of glass or a steel file. A genuine ruby will not scratch easily, and the surface should remain intact. Be cautious when performing this test, as it may damage a weaker or lower-quality ruby.
Testing Against a Diamond
If you have access to a diamond, it is the best material to test rubies for hardness. A real ruby will not be scratched by a diamond, while a fake ruby, such as one made from glass, will show visible signs of scratching.
5. The UV Light Test
Rubies react uniquely under ultraviolet (UV) light, particularly natural rubies.
Fluorescence Under UV Light
Many rubies exhibit a red or pinkish glow when exposed to UV light, especially those from Myanmar (Burma). This fluorescence is caused by the presence of chromium in the ruby. If you shine a UV light on the stone and it glows brightly, it is a strong indication of a genuine ruby.
Synthetic Rubies and Fluorescence
While many natural rubies fluoresce under UV light, synthetic rubies can behave differently. Some synthetic rubies may not fluoresce as strongly or may not fluoresce at all, making this test a helpful diagnostic tool in combination with other tests.
6. The Loupe and Magnification Test
For the most detailed examination, a jeweler’s loupe or microscope will provide a closer look at the ruby’s internal features.
Internal Structure
Under magnification, natural rubies often exhibit irregular inclusions, such as rutile (silk), that can be difficult to replicate in synthetic rubies. Many synthetic rubies, especially those grown in a laboratory, have inclusions that appear more regular and organized. By inspecting these inclusions, you can get a sense of whether the ruby is natural or synthetic.
Facet Examination
Examine the facets of the ruby under magnification to check for sharp, well-defined edges. Synthetic rubies may have poorly defined facets or smooth edges that are typical of lower-quality manufacturing processes.
7. The Refractometer Test
This is a more advanced technique that requires a refractometer, a device used by gemologists to measure the refractive index (RI) of gemstones.
Measuring Refractive Index
The refractive index of a ruby ranges from 1.76 to 1.77. A refractometer can help you determine the RI of the gemstone by measuring how light bends as it passes through the ruby. This test requires precision, and the results can confirm whether the ruby is genuine or synthetic.
Conclusion
Testing rubies at home can be an effective way to assess their authenticity before committing to a purchase. While these methods are not foolproof, they provide valuable insights that can help distinguish real rubies from imitations. Visual inspection, heat tests, the water test, and UV light testing are all practical and accessible methods.
For more conclusive results, professional gemological tools like refractometers and magnification can offer definitive answers. Always proceed with care, especially when performing tests that could potentially damage the gemstone.
Related topics:
