• PGGL Light Behavior Certificate PGGL Light Behavior Certificate
  • SAMPLE - PGGL Grading Certificate1 - Copy SAMPLE - PGGL Grading Certificate1 - Copy
  • Diamond Comparison_4 Diamond Comparison_4

Your diamond means a lot to you for many different reasons. At Precision Gem Grading Laboratory, it is our priority to make sure that bringing the most accurate and top quality diamond grading to trade and consumers in Philadelphia’s tri state area has been an important objective for Precision Gem Grading Laboratory (PGGL). PGGL offers grading, jewelry grading, appraisal, and sorting services for diamonds and mounted diamond jewelry to consumers and trade. Special consultation services are available for consumers that are looking to buy that special diamond. Besides the standard services, PGGL specializes in offering services using high tech gem grading machines from ImaGem Inc.

Using the world’s most advanced, state-of-the-art equipment by ImaGem® , PGGL grades diamonds, gemstones, and jewelry on light behavior, the 4 Cs, fluorescence and more. ImaGem’s patented direct measurement technology enables us to achieve very high levels of accuracy and repeatability. High levels of accuracy and repeatability in grading are important to everyone in the business, especially the end consumer. An error of just one grade in measuring the color, clarity or light behavior of a diamond can change the value of a diamond anywhere from a few hundred to a few thousand dollars.

We offer Light Behavior certificates for mounted diamond jewelry as well as loose diamonds. A wide range of grading certificates (with information on 4Cs, light behavior, fluorescence and more) are available for loose diamonds or diamond jewelry. Appraisal services for gemstones, jewelry, diamonds, and diamond jewelry for insurance, estate evaluation etc. are also available.

As more consumers become aware of the dangers of diamond switching, they are starting to put their faith in non-invasive diamond registration services to secure their diamonds. There is always a risk that diamonds may get switched during repairs, manufacture, cleaning etc.  Our newest service, ImaGem Secure Diamond Registration, is available to record the identity of your diamond jewelry for verification or confirmation as needed.

For more information or to set up an appointment,
call +1.215.774.9406 or send an email to

Precision Gem Grading Laboratory is owned and operated by ABM, LP, a Pennsylvania Corporation.