The Magnetic Attraction of Gemstones: A Closer Look

Gemstones have long captivated the human imagination, with their dazzling array of colors, shapes, and unique properties. One fascinating aspect of these natural wonders is their interaction with magnetic fields. While some gems are highly responsive to magnetism, others exhibit a more subtle or even repellent behavior. In this comprehensive exploration, we delve into the intriguing world of magnetic separation of gemstones, uncovering the science behind this phenomenon and its practical applications.

The Power of Magnets

Historically, the use of magnetic separation in gemstone identification was hindered by the limited strength of available magnets, such as aluminum nickel cobalt (Alnico). However, the advent of powerful neodymium iron boron (NdFeB) magnets has revolutionized this field. These magnets, which are many times stronger than their predecessors, have opened up new possibilities for a closer examination of gem materials and their magnetic characteristics.

Experimental Approaches

In this study, we employed three distinct methods to investigate the magnetic properties of various gemstones:

Direct Method

In this approach, a rod-shaped magnet was used to directly pull responsive, loose, faceted, and cabochon gems across a low-friction surface. This method provided a straightforward way to assess the magnetic attraction of the specimens.

Pendulum Method

A pair of magnets was snapped over a suspended thread, creating a pendulum. Gem specimens were either hand-held or suspended in a gem bag, and the movement of the pendulum was observed as the magnet interacted with the sample. This technique proved particularly useful for testing rough material, gems in non-magnetic settings, and large faceted specimens.

Floating Method

In this method, the gem under test was floated on the surface of a liquid (water), while the magnet was slowly brought into proximity. Alternatively, the magnet could be floated while the unknown gemstone was moved toward it. This approach was the most sensitive of the three, allowing for the detection of even the most subtle responses.

Observations and Discussions

The test results revealed a range of responses from the gemstones, with some being attracted to the magnet, others being repelled, and some showing no response at all. Gems containing iron (Fe) and/or manganese (Mn) in their chemical formulas tended to exhibit a stronger magnetic response, with Mn-rich specimens displaying the most pronounced attraction.

Interestingly, some gems that are typically considered non-responsive sometimes displayed a response due to various factors, such as the presence of inclusions or impurities. The floating method, in particular, was able to detect even the most subtle responses, making it a valuable tool for distinguishing between similar materials, such as garnet-topped doublets and turquoise versus plastic.

It's important to note that the magnetic response of a gemstone can be influenced by its setting, as many commonly used alloys contain ferromagnetic elements. Therefore, it is essential to test the gem setting as well, to ensure accurate identification.

Conclusions

The study of the magnetic properties of gemstones has proven to be a valuable tool in the initial screening and identification of these natural marvels. While the results obtained through magnetic separation are not diagnostic on their own, they can provide a useful starting point for further gemmological testing and analysis.

As the field of gemstone research continues to evolve, the understanding of magnetic interactions will undoubtedly deepen, leading to even more refined and efficient methods of gemstone identification and classification. The magnetic attraction of gemstones remains a captivating aspect of these geological treasures, inviting us to delve deeper into the intricate relationships between the natural world and the forces that shape it.

this atricle was made possible by Sylvia Gumpesberger' research