Yellow sapphire, with its unique yellow glow and precious attributes, has been cherished by people since ancient times. However, the market is flooded with a dazzling array of yellow sapphires, making it difficult to distinguish the real from the fake. To help you better understand and identify genuine yellow sapphire, this article will introduce identification methods from multiple perspectives.
Basic Overview of Yellow Sapphire
Yellow sapphire, often referred to as yellow crystal or topaz in mineralogy, is a gemstone with a rich variety of colors. Besides yellow, yellow sapphire also comes in blue, sky blue, golden, red, pink, and other precious varieties. The English name for yellow sapphire originates from the ancient name “Topaz” for the Zabargad Island in the Red Sea, which was once renowned for its abundant production of peridot gemstones. Yellow sapphire has been a precious gemstone since ancient times. Although its value is slightly lower than that of ruby and sapphire, high-quality varieties such as “Madeira Yellow Sapphire,” with a hardness greater than crystal, still command considerable value.
Methods for Identifying Genuine and Fake Yellow Sapphire
Observing the Fracture Surface
The fracture surface of natural yellow sapphire will exhibit a stone-like texture, distinctly different from the smooth feel of glass. As yellow sapphire is a mineral and crystalline solid, its fracture surface will not be as smooth and flat as glass, but will retain some stone-like qualities. In contrast, imitation yellow sapphire, often made of glass to achieve a similar transparency and gloss, will have a very smooth fracture surface.
Feeling the Texture
Yellow sapphire, as a crystal, conducts heat very quickly. When held in the hand, it will initially feel cool, and its temperature will gradually synchronize with body temperature over time. Imitation yellow sapphire, made of materials like glass or plastic with poorer thermal conductivity, will not feel cool in the hand, and its temperature will not change significantly.
Observing Imperfections
During its formation, natural yellow sapphire undergoes various geological processes, resulting in internal imperfections such as inclusions, co-existing minerals, and fractures. These imperfections are normal in natural yellow sapphire and serve as important indicators for identifying its authenticity. Imitation yellow sapphire, constrained by its internal structure and material, finds it difficult to replicate these imperfections, often appearing very clean and flawless internally.
Professional Identification Tools and Techniques
Magnifying Glass Observation
Using a 10x magnifying glass to observe the internal structure of yellow sapphire, one can discover imperfections like inclusions and fractures in natural stones. Imitation yellow sapphire, on the other hand, often appears perfect and flawless internally, as it is challenging to replicate these imperfections.
Polariscope Examination
A polariscope is a commonly used tool in gemstone identification. By rotating a yellow sapphire 360 degrees under a polariscope, one can observe changes in color. Natural yellow sapphire will display a pattern of four bright and four dark areas, while imitation yellow sapphire will not show such changes.
Refractive Index and Specific Gravity Measurement
The refractive index and specific gravity of yellow sapphire are important indicators of its physical properties. Measuring these properties can help distinguish yellow sapphire from other similar gemstones. For example, yellow crystal has different refractive index and specific gravity values compared to yellow sapphire.
Dichroscope Examination
A dichroscope is another commonly used tool in gemstone identification. Certain varieties of natural yellow sapphire exhibit dichroism, meaning they display different colors in different directions. Imitation yellow sapphire, however, usually does not possess this characteristic.
Absorption Spectrum Measurement
Certain varieties of yellow sapphire produce specific absorption spectral lines when heat-treated. Measuring the absorption spectrum of yellow sapphire can further confirm its authenticity. For example, genuine yellow sapphire will have two closely spaced weak absorption lines near 6820 angstroms, which imitation yellow sapphire will not have.
Distinguishing Yellow Sapphire from Other Gemstones
Distinguishing from Yellow Crystal
Yellow crystal is a transparent gemstone with a soft yellow color. Although similar in color to yellow sapphire, they differ in physical properties and internal structure. For instance, yellow crystal has lower refractive index and specific gravity than yellow sapphire. Furthermore, yellow crystal does not fluoresce under ultraviolet light, while yellow sapphire exhibits a pale yellow or pale green fluorescence.
Distinguishing from Yellow Sapphire (Corundum)
Yellow sapphire (corundum) is a gemstone in the corundum family. Although similar in color to yellow sapphire, they differ in chemical composition and internal structure. Yellow sapphire (corundum) fluoresces in an apricot color under long-wave ultraviolet light, while yellow sapphire exhibits a pale yellow and green fluorescence. Additionally, yellow sapphire (corundum) has a slightly higher hardness than yellow sapphire.
Distinguishing from Synthetic Yellow Sapphire
Synthetic yellow sapphire is artificially produced. Although it may resemble natural yellow sapphire in appearance, it differs in physical properties and internal structure. For example, synthetic yellow sapphire is often very clean and flawless internally, while natural yellow sapphire contains imperfections. Furthermore, the refractive index and specific gravity of synthetic yellow sapphire may also differ from those of natural yellow sapphire.
Common Imitations of Yellow Sapphire in the Market
Glass Products: Glass is a common material for imitating gemstones. Due to its low cost and ease of production, glass products are very common in the market. However, glass products significantly differ from natural yellow sapphire in refractive index, specific gravity, and hardness, making them easy to identify.
Melted Crystal: Melted crystal is produced by melting crystal or glass scraps. Although it may resemble natural yellow sapphire in appearance, it differs in internal structure and physical properties, making it easy to identify.
Lead Glass: Lead glass is a glass product with added lead, known for its high refractive index and good gloss. It is often used to imitate yellow sapphire. However, lead glass has a lower hardness and higher specific gravity compared to natural yellow sapphire.
Synthetic Crystal: Synthetic crystal is artificially produced. Although it may resemble natural crystal in appearance, it differs in internal structure and physical properties, making it easy to identify. Furthermore, synthetic crystal often lacks the unique oily luster of natural crystal.
Conclusion
Identifying the authenticity of yellow sapphire requires consideration of multiple factors, including fracture surface, texture, imperfections, and the use of professional identification tools. Through careful observation and comparative analysis, one can effectively distinguish between natural and imitation yellow sapphire. Additionally, understanding the differences between yellow sapphire and other similar gemstones is crucial. This article aims to provide a better understanding and guidance for identifying the authenticity of yellow sapphire, serving as a useful reference for purchasing and collecting yellow sapphire.
Related topic:
- Crafting Necklaces with Indian Sapphires: A Step-By-Step Guide
- [Revealed!] The Meaning of Leibish Sapphires in Color & Jewelry
- The Meaning of Triangle Sapphires: What You Need To Know
