Exploring the World of Gemstones: The Art of Gem Identification Under the Microscope


As the gemstone industry continues to grow, more and more people are buying gemstones. The booming gemstone market has brought about economic development, but very often the proliferation of fake gemstones has become a problem for consumers. Although we are able to find some easy identification methods with the help of the internet. For example, visual inspection method (that is, using a magnifying glass or a microscope to analyze and observe the internal condition of the gemstone, cut, etc.), specific gravity determination method (by measuring the density of the gemstone to determine the authenticity of the gemstone), microscope observation method (using a special gemstone microscope or stereo microscope to observe the internal inclusions of the gemstone) and so on. But very often, the only way to distinguish between natural and synthetic gemstones is by observing and analyzing the microscopic inclusions inside the gemstone. This is why a microscope has become an essential tool for gemologists and gemstone collectors. If you are interested in purchasing a microscope for gemstone observation, the following knowledge may be of some help to you.

About the focusing method of the microscope

Suffice it to say that every microscope will have two component parts that control the magnification of the enlarged image. One is a device for initial adjustment and the other is a device for accurate adjustment. The most important thing in assessing how good a focusing device is is how stable the accessory that controls the focusing is. This is because the more stable the adjusting accessory is, the more accurately the microscope will focus during the imaging process. In addition, it can ensure that the image will not be shaken during the process of moving the object to be observed.

How do I adjust the eyepiece of a microscope?

The eyepiece adjustment steps of the microscope can be done as follows (if it is your first time to use the microscope, you’d better read the manual well first, it is important to learn some basic operations).

  1. First set the microscope’s magnification to maximum
  2. Turn on the microscope’s overhead light.
  3. Observing objects with one eye through a non-adjustable eyepiece
  4. Observation of a feature of an object
  5. Observe objects with the other eye through an adjustable eyepiece
  6. Adjust the eyepiece focal length according to the actual situation (note that the adjustment here is for the eyepiece not the objective lens)
  7. Observe the object with both eyes until the object is all clear in the imaging (if you still can’t see it clearly, you repeat the steps above).


The microscope needs to have a workbench that is large enough. The table is only big enough to accommodate more sizes of jewelry or gemstones. This is when a movable and rotatable stand is important. This is when your workbench can be fully utilized.

How do I adjust the magnification?

When you first start using a microscope, you’re best off using a low magnification, usually 20x. Once you can observe the inner material of the gemstone, you can switch to an eyepiece with a larger magnification to see more details.

In addition to changing the eyepieces to adjust the magnification as mentioned above, you can also adjust the magnification by turning the adjustment knob. Generally speaking, the better the function of the adjustment knob, the more expensive the microscope will be sold.

Microscope light

Generally, stereo microscope’s have two separate light paths. While these two separate light paths are generally enough for the average gem collector to make observations. However, for more specialized gemologists, two lights are generally not enough. They generally choose to purchase an additional light, which can be a penlight or a desk lamp. There is generally no set standard for this, it can be any lamp as long as you use it well. A good microscope will also come with a light source with a dark field of view and an adjustable aperture. But for the average person this is not a necessity.

Illumination techniques for microscopes

As one of the most important techniques of microscopy, illumination is also a very important reference for selecting a microscope. Because there are so many optical features inside a gemstone, it can also be used as an indicator to distinguish the authenticity of a gemstone or to assess the quality of a gemstone. Take diamonds as an example. Carbon inclusions inside diamonds are easy to observe because they are, after all, opaque. In contrast to carbon inclusions, most of the crystalline inclusions inside other gemstones are transparent, so they are not as easy to observe. Another element is the refractive index. Sometimes the refractive index of the outside of the gemstone and the inclusions of the gemstone are different. Two objects with different refractive indices are very visible under a microscope.

If you want to completely figure out what kind of inclusions the inside of a gemstone actually contains. You may need to keep adjusting the light source of the microscope. This is because sometimes a gemstone can contain multiple inclusions, sometimes in a layered structure.

How do I use a microscope to look at gemstones?

Before you start looking at the gemstone, it is a good idea for you to have the gemstone carefully cleaned. This includes dust, as well as fingerprints that you accidentally stuck to the gemstone when you were holding it. All of these things can interfere with your subsequent observation of the gemstone.

You can then start looking at the gemstone with a lower magnification lens, and at first you may choose to use the microscope’s overhead light as a light source for looking at the gemstone. If you find inclusions inside the gemstone, then you can use a higher magnification to look at the gemstone’s inclusions.