Step 3: Practical Gemology

Lesson 18

Zandrite is a synthetic glass with color change properties. It can be manufactured to show different color changes, even green to red, like alexandrite. However, among other differences in optical and physical properties, zandrite has a moderate to strong magnetic reaction, while alexandrite is inert. 7.80-ct zandrite, 14 mm round. Photos courtesy of liveauctioneers.com and Advantage Auction Company.

A Confirmative Test, Not a Determinative Test

Some time ago, I became interested in gemstone magnetism. While researching this property, I found that some gemology schools had little to say on the subject. (Many gemology books fail to list magnetic attraction as a gemstone property at all). Most think magnetism testing isn’t reliable enough to use with any success in gemstone identification. I disagree with that position. However, I think this property should be used as a confirmative test only, not a determinative one.

Gemstone magnetism is a very complex subject, so I decided to test this property in the simplest of ways in order to find an easy way to measure it. I hope someday there will be an accurate and easy way to measure magnetic susceptibility or magnetic characteristics…