© Kirk Feral 2009-2016, All Rights Reserved. These materials may be duplicated and shared for educational purposes only. No part of this website may be duplicated or distributed for profit, for commercial purposes, or for posting to another website, without the expressed written consent of the copyright holder.
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Click on this link to read continue reading: Overview of Magnetism in Gemstones
The intent of this website is to introduce the magnetic wand and testing method to gem hobbyists, professional gemologists and researchers, and to demonstrate the remarkable effectiveness of magnetic testing. The value of quantitative measurements of magnetism in gemstones using a Hoover balance is also demonstrated, with particular emphasis on Garnet identification. The information in this website can be used as supplemental course material for gem identification classes. Gem ID course instructors may freely print or digitally share website content copyrighted by this author.
Much of the information regarding magnetism in gemstones provided throughout this website, including all reference charts and research results, is new information that has not been published elsewhere. This information was developed by this researcher through investigation of magnetism in thousands of gems in private collections. The Magnetic Susceptibility Index, developed and maintained by this researcher since 2009, is the only published index that provides both qualitative and quantitative measurements of the magnetic susceptibilities of most gemstones. All photos, except where noted, were taken by the author.
The concept of using a hand-held magnet as a gem identification tool is not new. Renowned British gemologist Basil Anderson proposed it in 1953. More recently, Sylvia Gumpesberger (2006) and a few other researchers have published preliminary investigations of gem testing using stronger rare-earth magnets (see Resources and Links). But for the most part, the practical value of magnetic testing has been overlooked or dramatically underestimated. As of 2016, the magnetic wand remains unfamiliar to most gemologists, students, collectors, jewelers, and gem dealers.
This website provides information to help you get started using this tool, including: 1) an overview of magnetism in gemstones 2) how to use a magnet for gem identification, and where to buy magnets 3) an index of magnetic responses for 350 gem and mineral species and color varieties, and 4) a reference chart for separating look-alike gems. Additionally, individual sections of this website provide an in-depth look at the magnetism of Diamond, Sapphire & Ruby, Tourmaline, Garnet and Spinel. These gem-specific sections review how magnetic responses and measurements can help us with identification of these gem types.
If you collect, sell, or work with gems and need to know how to identify them, a magnet belongs in your set of standard testing tools, alongside your refractometer, specific gravity tester, microscope, polariscope, dichroscope and spectroscope. Once you start working with a magnet, you'll find magnetic testing quickly becomes an essential part of the identification process for all Colored Stones, as well as Diamonds.
A magnetic wand made from the rare earth element neodymium is one of the most useful, and least known, tools for basic gem identification. Because every type of gem shows a characteristic range of responses to a neodymium magnet, we can use such magnetic responses to help us identify gems. A magnetic wand is an extremely sensitive instrument that can detect very slight magnetism. Wands are small and portable, and simple to use. Unlike many other gemology tools, neodymium magnets are accessible to everyone. Wands can be easily assembled for just a few dollars.
3 Examples of Magnetic Responses
How is it Useful?
The Forgotten Tool
Aquamarine is Weakly to Moderately Attracted to a Magnet
Natural Blue Spinel
Shows Magnetic Attraction
Topaz of Any Color
is Not Attracted
to a Magnet
Synthetic Spinel is Not Attracted to a Magnet
"Magnetic testing as Feral describes should be in the tool kit of all practicing gemologists."
Dr. D. B. Hoover FGA
Among its multiple uses, a magnetic wand provides a quick means for identifying Garnet. Most Garnets pick up. Differences in magnetic response can also be used to distinguish some natural gems from synthetics and imitations. For example, natural blue Spinel can in most cases be distinguished from synthetic blue Spinel, and natural Diamond can often be separated from lab-created Diamond. A magnet can be used to separate many types of gems that look alike, such as Aquamarine from blue Topaz, or Chrome Tourmaline from all other green Tourmalines. And magnetic testing can serve as an important method to corroborate the test results of your other gemology tools. Many more uses are presented on the page titled 10 Practical Uses for Gem Identification.
Magnetism in Gemstones
An Effective Tool and Method for Gem Identification
© Kirk Feral 2009-2016
Magnetism is a physical property that can be measured in minerals and cut gemstones. The study of magnetic properties is a long-established discipline of geology and mineralogy, but its application to gemology is still largely ignored. The simple method of testing described in this website is missing from the curriculum of gemology classes taught by gemology institutes, universities and gem & mineral societies. Research on this method and its practical applications is scarce, and the importance of magnetism to gemologists is not recognized in gemology books, journals or online resources. Discussion of the magnetic properties of gemstones is conspicuously absent from most compendiums and indexes of gems.
Peridot is Dragged
by a Magnet