Buzz
Many so-called 'emeralds' are actually various types of green gemstones, green glass, or fake gems made from different materials. It's crucial to conduct several tests before concluding whether a gem is real or fake, as results may not always be accurate without specialized gemological equipment. If you have an emerald, you may want to test if it's a natural emerald or a synthetic one created in a laboratory.
Steps to Follow
Evaluating an Emerald
Examine the gemstone under a magnifying glass or jeweler's loupe to spot flaws. Ideally, use a jeweler's loupe with 10x magnification. Hold the loupe so that light shines at an angle on the gemstone, ideally creating a narrow light beam. If you notice tiny blemishes or uneven patterns, it's likely a real emerald—although not necessarily an emerald. If the stone is flawless, with almost no 'inclusions,' it could be a synthetic emerald (man-made but real) or not a gemstone at all. Bubbles, which are commonly found near inclusions in natural emeralds, can also appear. If you see only a cluster of bubbles with no other inclusions, the gem might be glass, though it could also be a synthetic emerald.
Kiểm tra hiệu ứng lấp lánh. Ngọc lục bảo thật sẽ không hoặc rất ít phản chiếu “ánh lửa” tức là các tia sáng loé nhiều màu sắc xuất hiện dưới ánh sáng. Nếu viên ngọc của bạn phát ra các tia sáng bảy sắc cầu vồng thì nó không phải là ngọc lục bảo.
Quan sát màu sắc. Đá beryl chỉ được gọi là ngọc lục bảo nếu nó có màu xanh lục thẫm hoặc lục - lam. Đá beryl có màu vàng chanh được gọi là heliodor, và đá beryl có màu xanh lục sáng có tên gọi đơn giản là đá beryl xanh. Ngọc màu vàng chanh cũng có thể là olivine hoặc ngọc hồng lựu xanh.
- Ranh giới giữa ngọc lục bảo và đá beryl xanh rất mỏng manh – hai người thợ kim hoàn có thể không nhất trí trong việc phân loại một viên ngọc.
Xem xét độ mòn của các mặt cắt. Thủy tinh và các vật liệu mềm khác thường nhanh mòn. Nếu cạnh của các mặt cắt trông mềm và mòn thì viên ngọc đó có thể là giả. Thủy tinh giả ngọc thường có các kết cấu lồi lõm "vỏ cam" và các cạnh của mặt cắt hơi tròn. Bạn hãy tìm các đặc điểm trên bằng kính lúp.
Kiểm tra các lớp. "Đá ghép" giả ngọc được chế tạo từ hai đến ba lớp vật liệu khác nhau, thường có một lớp màu xanh giữa hai lớp đá không màu. Nếu viên đá chưa được gắn vào trang sức, bạn có thể dễ dàng thấy được các lớp này khi ngâm viên đá trong nước và quan sát từ mặt bên. Nếu viên đá đã được gắn vào trang sức thì sẽ khó thấy hơn một chút, nhưng bạn có thể thử quan sát ở các rìa xung quanh xem có sự thay đổi màu bất thường không.
Quan sát ngọc lục bảo qua kính lưỡng sắc. Một số loại đá quý hiện lên các màu sắc khác nhau khi nhìn từ các hướng khác nhau, nhưng bạn chỉ cần dùng một công cụ khá rẻ gọi là kính lưỡng sắc để phân biệt. Đặt viên đá sát vào một đầu của kính lưỡng sắc và nhìn qua ô quan sát. Viên đá sẽ được chiếu sáng bằng nguồn ánh sáng khuếch tán mạnh và trắng như bầu trời đầy mây. Xoay viên đá và kính lưỡng sắc để quan sát từ mọi hướng. Ngọc lục bảo thật sẽ toả ra hai sắc, màu xanh lục-lam khi nhìn từ góc này và màu vàng chanh từ góc khác.
- Tính lưỡng hướng sắc mạnh (hai màu rất rõ rệt) là dấu hiệu của ngọc lục bảo chất lượng cao.
- Kết quả có thể không theo quy luật do hiện tượng phản xạ trong từ một bề mặt, do các đặc tính của ánh sáng đèn huỳnh quang hoặc do ánh sáng chạm đến ô quan sát mà không chiếu qua viên đá. Ngoài cách này, bạn nên sử dùng thêm các phương pháp khác để có kết quả chính xác thay vì chỉ dùng một phương pháp.
Be cautious of cheap stones. If the deal seems too good to be true, trust your instincts. Natural emeralds, with their vivid green color, typically cost at least 11 million VND per carat. If the price is unbelievably low, the stone is likely to be glass or crystal, not a genuine emerald. Synthetic emeralds are much cheaper than natural ones but still cost more than most other synthetic stones. A small synthetic emerald may cost around 1.5 million VND per carat.
Kennon Young
Gemstone Expert
Gemstone Expert
If the emerald is set in jewelry, you should also inspect the setting. If the gem is held by glue rather than prongs, it might be fake. Additionally, if you notice round cutting lines, the stone is likely molded or plastic.
Have the Stone Professionally Assessed. If you are still unsure, take the stone to a jeweler for a professional evaluation. Jewelers use specialized tools to give you an accurate answer, along with a detailed description of your gem.
- Look for jewelers accredited by a national organization, such as the Gemological Institute of America or the American Gem Society. A certification in gemstone trade is also beneficial.
- Avoid appraisers with ties to specific retailers, especially those who are trying to sell you the gem you want appraised.
- Appraisal fees can vary greatly and may be charged per item, by the hour, or per carat. You should avoid services that charge a percentage of the emerald's value.
Identifying Synthetic Emeralds
Understanding synthetic emeralds. Synthetic emeralds are created in a laboratory and have the same chemical composition as natural emeralds. They are real emeralds, but are much cheaper due to lower production costs. If you suspect someone is trying to sell you a synthetic emerald at an inflated price, try the following tests:
- For a more reliable test, move on to the next step and use an emerald filter lens.
- If you prefer not to buy a filter lens, you can try other tests. These tests still require some tools as synthetic emeralds are very difficult to distinguish with the naked eye.
Using a filter lens
Purchase 3 types of emerald filter lenses. You can purchase a Chelsea filter, a synthetic emerald filter, and a confirmation filter online. The latter two are called "Hanneman filters" and can be sold as a pair. The price for all three lenses is around $60 (about 1.2 million VND), so it might not be worth buying if you're only testing a single stone.
- In some cases, you may also need a jeweler's loupe to closely examine the emerald. Most emeralds don’t require this tool for observation.
Observe through the Chelsea filter lens. The first step is to examine the emerald using the Chelsea filter lens:
- Place the emerald under incandescent light on a white background (fluorescent light may distort the results).
- Use a tissue to cover the metal or other stones attached to the emerald to prevent any reflected colors.
- Hold the Chelsea lens close to your eye and focus on the color you see through the lens from a distance of about 25 cm or slightly closer.
- If the emerald appears red through the Chelsea filter, proceed to the next step and test with the synthetic filter lens.
- If the emerald appears green through the Chelsea filter, move on to the confirmation filter test.
- If the emerald appears red-purple, it’s synthetic. You can verify the color by viewing it through both the synthetic and confirmation filters – if the stone appears green through both, it’s synthetic. If it appears green through the synthetic filter but red through the confirmation filter, it’s a natural emerald.
The next step is to use the synthetic filter lens. If the emerald appears red or pink through the Chelsea filter, it indicates the presence of chromium. Both natural and synthetic emeralds can contain chromium, so you need to differentiate them using the synthetic filter in the testing kit:
- Hold the emerald about 10 cm away from the light source and examine it through the synthetic filter lens.
- If you still see red or pink, the emerald is a synthetic one created using flux growth.
- If you see green, it's a natural emerald, possibly from Colombia or Russia.
Observer confirms the gemstone through the confirmation filter. This method is only useful if the gemstone appears green through a Chelsea filter. Follow these steps:
- Move the gemstone about 10 cm away from the light source and examine it through the synthetic filter.
- If the stone displays a bluish-green, mauve, or pink color, it is likely a synthetic emerald made through the hydrothermal method.
- If the gemstone still appears green (not bluish-green), proceed to the next step.
Inspect the emerald using a jeweler's loupe. If the stone shows a green hue through both the Chelsea filter and the confirmation filter, it could be a natural or synthetic emerald. Fortunately, synthetic emeralds that match this description usually have distinct characteristics from natural ones. You can inspect the emerald with a jeweler's 10x loupe:
- If the emerald is clear and nearly flawless, it is almost certainly a hydrothermal synthetic emerald.
- If the loupe reveals several tiny flaws (such as needle-like crystals, cloudiness, etc.), the gemstone is likely a natural emerald containing vanadium and/or iron, such as those mined from emerald deposits in Zambia, Brazil, and India.
Other testing methods
Examine the inclusions. Initially, synthetic emeralds had very few inclusions compared to the many small imperfections found in natural emeralds. Later, synthetic gemstone technology introduced more inclusions, although some types are unique to natural emeralds. If possible, look for the following features under a jeweler's loupe or microscope:
- If the emerald contains an "inclusion" with both bubbles and crystals, it is likely a natural emerald. This is known as a "three-phase inclusion."
- Some crystals only appear in natural emeralds: green actinolite fibers resembling bamboo, mica scales, or pyrite crystals.
Test the emerald with ultraviolet light. For this method, you'll need a "long-wave" ultraviolet light – the cheapest and most commonly available type. Bring the emerald into a dimly lit or dark room, shine the ultraviolet light onto the gemstone, and observe the fluorescence color:
- Yellow, olive-green, or bright red fluorescence strongly indicates a synthetic emerald.
- If there is no fluorescence, the stone might be a natural emerald, though this isn't definitive. Some synthetic emeralds also lack fluorescence.
- Pinkish or reddish-orange fluorescence could indicate either a natural or synthetic emerald.
Advice
- A refractometer is a fantastic tool for identifying gemstones, but it can be expensive and tricky if you haven't learned how to use it. If you are able to use a refractometer, check if the gemstone's refractive index falls within the range of 1.565 to 1.602, which is the typical refractive index of natural emeralds. Also, make sure to check the birefringence (double refraction) – which is around 0.006. Synthetic emeralds have a birefringence around 0.006 or much lower, and their refractive index is typically between 1.561 and 1.564 or can go up to 1.579. If the results fall outside of this range, the stone is most likely a fake.
- The terms that sound like the name of a country of origin ("Colombia"; "Brazil") actually only refer to the appearance of the gemstone. Each region that typically produces emeralds tends to have a specific color range, and emeralds matching that description are often named after the region. This is just a general rule, as every region can produce a variety of different emerald types.
Warnings
- Emeralds are resistant to scratches, but their brittleness makes them prone to breaking when struck. A hammer is not an appropriate tool for testing an emerald!
