In the world of jewelry, rubies are highly sought-after for their unique charm and rarity. However, with the continuous advancement of synthetic technologies, more and more synthetic rubies that can pass as genuine are appearing on the market. As jewelry appraisers, one of our core responsibilities is to accurately distinguish between natural and synthetic rubies. This article will provide a detailed introduction, from a professional perspective and in an easy-to-understand manner, on how to identify whether a ruby is synthetic.
Basic Characteristics of Rubies
A ruby is a type of corundum, primarily composed of aluminum oxide (Al₂O₃), and it owes its red color to the presence of trace amounts of chromium. Natural rubies come in various shades of red, including deep red, purplish red, and pink, with pure red being rare. Their color is often uneven, with possible variations in shade locally, due to natural conditions and impurities during the gemstone’s formation. Rubies have a very high hardness, second only to diamonds, with a Mohs hardness of 9, making them ideal for jewelry making.
Manufacturing Methods for Synthetic Rubies
Currently, there are three main methods for synthesizing rubies: the Verneuil process, the flux-growth method, and the hydrothermal method.
1. The Verneuil process involves melting aluminum oxide powder with a high-temperature flame and crystallizing it into a ruby. Synthetic rubies produced by this method often have arc-shaped growth patterns and bubbles inside, which can serve as important identifiers during appraisal.
2. The flux-growth method uses a flux to facilitate the crystallization of aluminum oxide under high temperature and pressure. The internal characteristics of rubies synthesized this way are more concealed and require observation under a high-powered microscope by professionals for identification.
3. The hydrothermal method simulates the natural growth environment of rubies, using high-temperature and high-pressure aqueous solutions to synthesize them. Rubies synthesized by the hydrothermal method have internal characteristics that are very similar to natural rubies, making identification challenging. It often requires the use of large instruments such as X-ray machines.
Differences between Natural and Synthetic Rubies
Color and Uniformity
Natural rubies are rarely perfectly uniform in color; the conditions under which they form result in local or slight variations in hue. In contrast, synthetic rubies are usually very vivid and uniform in color, with no visible inclusions, giving them a very clean appearance. This is because synthetic rubies undergo precise control and treatment during manufacturing to achieve optimal color effects.
Inclusions
Natural rubies are rich in inclusions, with impurities varying depending on the origin, serving as unique identifiers. These inclusions may include mineral crystals, gas bubbles, cracks, etc. Synthetic rubies, on the other hand, are clean and free of these natural inclusions. Under a microscope, synthetic rubies may show bubbles or unmelted powder, with bubbles mostly being small and round or tadpole-like, appearing singly or in groups.
Crystal Structure
Natural rubies have complex crystal structures, often exhibiting geometric polyhedral forms. Synthetic rubies, in contrast, have relatively simple crystal structures, with the original crystal shape mostly being pear-like. Additionally, synthetic rubies may form typical arc-shaped growth patterns during growth, which differ significantly from the angular or hexagonal color zones of natural rubies.
UV Fluorescence
Both natural and synthetic rubies exhibit fluorescence under UV light. However, due to their pure composition and lack of inclusions, synthetic rubies have stronger and brighter fluorescence. Natural rubies, on the other hand, have relatively weaker UV fluorescence, with variations among multiple gems.
Size and Weight
Natural rubies are usually small, with 1-2 carat gems being common in the market. This is because the conditions for natural ruby formation are demanding, making large gems very rare. In contrast, synthetic rubies can be produced to any size according to demand. However, it’s worth noting that even though synthetic rubies can be made in larger sizes, their prices also rise significantly when reaching a certain weight (such as above 5 carats), due to the rarity and production difficulty of large gems.
Pleochroism
Natural rubies have weak pleochroism, which is difficult to observe with the naked eye. Synthetic rubies, however, may exhibit stronger pleochroism due to technological processing. Viewing from the table facet can reveal the gem’s pleochroism, which is also an important feature for distinguishing between natural and synthetic rubies.
Professional Appraisal Methods and Instruments
As jewelry appraisers, we typically use a series of professional detection techniques and instruments to accurately identify the authenticity of rubies. These instruments include:
- Magnifying glass: Used to observe the surface features and internal inclusions of rubies.
- Refractometer: Measures the refractive index of rubies to determine if they belong to the corundum category.
- Spectroscope: Analyzes the absorption spectrum of rubies to determine if they contain specific color-causing elements.
- Microscope: Observes the internal structure and inclusion characteristics of rubies under high magnification.
- X-ray machine: Provides important internal structural information for rubies that are difficult to identify, such as those synthesized by the hydrothermal method.
In addition, we also consider the gem’s weight, color, transparency, and cutting standards to comprehensively evaluate its quality and value. These standards are based on internationally recognized gem appraisal norms, ensuring the accuracy and authority of appraisal results.
How Consumers Can Guard Against Synthetic Rubies
For ordinary consumers, it is difficult to accurately distinguish between natural and synthetic rubies due to the lack of professional appraisal knowledge and instruments. Therefore, when purchasing rubies, consumers should pay attention to the following points:
- Check the certificate: When buying a ruby, always ask the seller to provide a formal jewelry appraisal certificate. These certificates are usually issued by authoritative jewelry appraisal institutions and contain detailed information about the gem, appraisal results, and the appraiser’s signature.
- Choose reputable sellers: When purchasing rubies, choose sellers with good reputations and credibility. These sellers usually provide quality after-sales service and safeguards to protect consumers’ rights and interests.
- Understand market prices: Before buying a ruby, learn about the current market prices and trends. This helps consumers judge whether the seller’s price is reasonable and avoid being deceived by high or low prices.
- Learn basic knowledge: Although consumers may not be able to master professional appraisal knowledge, understanding some basic ruby knowledge and appraisal techniques is still helpful. This can assist consumers in making wiser decisions during the purchasing process.
Conclusion
Rubies, as one of the treasures in the jewelry world, have won the admiration of countless people with their unique charm and rarity. However, with the continuous advancement of synthetic technologies, more and more synthetic rubies that can pass as genuine are appearing on the market. As jewelry appraisers, we have a responsibility and obligation to provide accurate and reliable appraisal services to consumers. By mastering professional appraisal knowledge and using advanced detection instruments, we can effectively distinguish between natural and synthetic rubies, ensuring that consumers’ rights and interests are not harmed. At the same time, we also hope that consumers can increase their vigilance, learn some basic identification techniques, and make wise choices when purchasing rubies.
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