Professor Wijojo, mineralogist from the University of Semerang will conduct the classroom training.

• Cheat Sheets for Gemologists
• Disclosing Enhancements
• Gem Testing Procedures
• How Gems Are Identified Part II: Deductive Reasoning
• Difficult Separations
• What is it? Gemstone Identification Quizzes
• Is it Worth It? Tips and Advice for Determining the Value of Gemstones
• Using The Refractometer
• Testing for Surface Treated Gems

DGL uses the "Flipped" classroom instructional methodology. This type of learning has the student study the IGS online instructional content prior to the class. In-class lessons are then used more to discuss, answer questions, have live demonstrations, hands-on training  and in other ways to engage students in the syllabus content.

Classes are taught in Bahasa Indonesia.