1. Research gemstone testers. Read reviews and compare features of different models to determine which one is best for your needs.

2. Determine your budget. Gemstone testers can range in price from a few hundred dollars to several thousand dollars.

3. Visit a local jewelry store or gemstone dealer to get a hands-on look at the testers. Ask questions and get advice from the experts.

4. Purchase the gemstone tester online or from a local store. Make sure to read the return policy before making your purchase.

5. Read the instructions carefully and practice using the tester before testing any gemstones.