A gem tester is a device used to identify the type of gemstone being tested. It is an important tool for gemologists and jewelers, as it can help them determine the value of a gemstone. Here is how to make a gem tester:

1. Gather the materials. You will need a gemstone, a light source, a magnifying glass, a pair of tweezers, and a gemstone testing kit.

2. Place the gemstone on a flat surface. Use the tweezers to hold the gemstone in place.

3. Shine the light source onto the gemstone. Use the magnifying glass to examine the gemstone closely.

4. Use the gemstone testing kit to identify the type of gemstone. The kit will usually include a set of probes and a chart that will help you identify the type of gemstone.

5. Record the results. Make sure to record the type of gemstone, its color, and any other relevant information.

6. Clean the gemstone. Use a soft cloth to remove any dirt or debris from the gemstone.

7. Store the gemstone in a safe place. Make sure to store the gemstone in a dry, cool place away from direct sunlight.

Following these steps will help you make a gem tester and accurately identify the type of gemstone you are testing.