How to Use a Gem Tester for Gemstones and Jewelry

A gem tester is a gemstone and jewelry testing tool that has a meter that indicates heat conductivity, and most have the color stone estimating function for preliminary testing of certain gemstones, too.

With the proper set-up and testing of a gemstone, the needle of the gem tester reveals the most likely simulant or diamond. It is particularly useful to be sure that a gemstone is not just colored glass.

Difficulty:

Moderately Easy

Instructions

Things You'll Need

• a gem tester
• gemstone or diamond to test

1. Read the instructions.

   Set up the gem tester according to the instructions. This involves plugging in the adapter and the probe pen and removal of the protective cap.

2. Wait for the center light.

   Turn the tester on with the on-off switch. Wait about 20 seconds for warmup. Press the probe to the simulant test disc and then to the diamond test disc to be sure that the needle is functioning properly. Wait for the center light.

3. Touch the pen to the gemstone or diamond.

   Use the probe pen and touch it to the gemstone or diamond with enough pressure to make the wire tip retract into the probe pen.

4. Read the meter.

   Observe the highest reading on the meter. This indicates the type of gemstone. Glass and cubic zirconia test on the low end, and the top end shows sapphires and rubies. The diamond goes to the far right so there is no confusion with a cz.

5. Compare the gemstones.

   Know that the gem tester will compare sapphire with tanzanite, iolite, spinel, citrine, topaz or tourmaline. It will compare the emerald with jadeite or garnet, and jadeite with chrysoprase or aventurine. The ruby can be compared with spinel or garnet and the topaz with aquamarine, citrine or garnet.

   This is a great little tool for a jewelry buyer or seller, and it is good to tell glass from a gemstone, a cz from a diamond, and any simulant from a diamond. The diamond tester is a better tool for diamonds exclusively.

Tips & Warnings

• We often write about jewelry and gemstones, and have other articles in Resources below.

• copyright 2009 Linda Richard

• Feel free to link to this article or send it to a friend. Do not copy.

Resources

• Use Electronic Gold Tester for Jewelry
• Use a Loupe
• Identify Sterling Silver Jewelry Content
• Identify Gold Jewelry by Marks
• Identify Gold Filled or Plated Jewelry
• Use a Gram Scale for Gold Jewelry
• Sell Fine Jewelry: Tools to Buy
• Find Antiques and Collectibles Appraiser