A Complete Guide to Identifying Topaz
Topaz has been a precious gemstone since ancient times due to its hardness and beautiful color. Topaz is used as the birthstone for November and the commemorative gemstone for the 16th wedding anniversary. Topaz symbolizes friendship and happiness.
Figure 1 Topaz of various colors
1. The color of topaz
Topaz comes in a variety of colors, including yellow, blue, pink, and colorless. Natural yellow topaz has a natural and soft tone, from light yellow to golden yellow; the blue of blue topaz is either fresh and elegant like the sky, or deep and rich like the ocean; pink topaz is like a girl’s cheek, exuding a gentle atmosphere.
If the color of the topaz is too bright and the color distribution is too uniform without any natural gradient, you need to be vigilant, it is likely to be artificially treated. For example, some blue topaz on the market is obtained by irradiating colorless or light-colored topaz.
Figure 2 Blue Topaz
2. Professional Instrument Identification
Professional instrument identification is one of the most effective identification methods. Here are several instrument identification methods.
(1) Detect the refractive index.
The refractometer can accurately detect the refractive index of topaz. The refractive index of topaz is very stable, generally between 1.619 – 1.627 (±0.010). The refractive index of orange, red, and yellow topaz is relatively high, and may be as high as 1.63-1.64.
(2) Detect density.
The density of topaz is generally 3.53 (±0.04) g/cm3. Using a balance and density accessories can accurately detect the density of topaz.
- Magnified observation
Using a gem magnifier and a gem microscope to magnify the topaz, natural topaz can be seen with some inclusions with characteristic identification significance, such as: gas-liquid two-phase inclusions, gas-liquid-solid three-phase inclusions, fluid inclusions, mineral inclusions, etc.
Figure 3 Gas-liquid two-phase inclusion
Figure 4 Gas-liquid-solid three-phase inclusion
Figure 5 Fluid inclusion
(4) Hardness test
Topaz is a standard hardness mineral with a Mohs hardness of 8. The hardness of topaz can be tested by scratching the surface of the gem with a hardness pen. This method is a destructive identification and is only suitable for identifying raw stones.
- By gemstone identification certificates issued by authoritative identification institutions
In gem trading, recognizing the gem identification certificate issued by an authoritative identification institution is like buying a quality insurance for the gem. It is not only an authoritative proof of the quality and value of the gem, but also a strong guarantee for the rights of consumers. How can we distinguish the authenticity of a gem identification certificate?
- Check the official website of the institution: Search the official website of the identification institution through the Internet to check the background, qualification certification, business scope and other information of the institution. The official website of the formal and authoritative institution has complete information and is updated in a timely manner. You can check the authenticity of the certificate and related detailed information. If you cannot find the official website or the official website information is simple and vague, you need to be wary of the authenticity of the certificate.
- Certificate number verification: Each authoritative identification certificate has a unique number, which can be entered on the institution’s official website for verification. If the query result is consistent with the certificate information, and the certificate format is standardized, the content is detailed, and the anti-counterfeiting mark is clear, the certificate can basically be confirmed to be authentic. If the number query is fruitless or the information does not match, the certificate is very likely to be fake.
(3) Anti-counterfeiting mark identification: Authoritative certificates usually use a variety of anti-counterfeiting technologies, such as laser anti-counterfeiting labels, watermarks, special paper, etc. Observe the certificate carefully, the anti-counterfeiting mark should be clear, fine and difficult to copy. For example, the laser anti-counterfeiting label will show unique patterns and gloss changes at different angles, and the watermark can be seen clearly under light.