In this comprehensive course, you’ll learn step by step how to better identify feldspars. Rolf Egberink will guide you through this often-overlooked group of minerals and, using examples from his own collection, show you how feldspars are structured, how they form, and how to distinguish them from one another in practice.

You’ll gain insight into the classification of potassium and plagioclase feldspars, learn what to look for when identifying them, and discover how characteristics such as crystal shape, cleavage, structure, and optical effects are related to the formation of these minerals. You’ll also learn how well-known stones such as moonstone, sunstone, amazonite, and labradorite fit into this group.

In this comprehensive online course, you’ll learn step by step how to reliably identify cut gemstones. Gemologist Henk Rijneveld FGA lets you look over his shoulder as he works with classic instruments such as the refractometer, polariscope, spectroscope, and dichroscope.

You’ll learn exactly what gemstones are, which characteristics are important for identification, and how to systematically reach a well-founded conclusion, with plenty of real-world examples.

In this mini-course, you’ll learn everything about the unique gemstone, the opal. Jeweler and collector Marloes Hoekstein (Steinisch) takes you on a journey into the world of opals’ play of colors, structure, origin, and care.
You’ll discover exactly what opals are, where they’re found, how to recognize them, and what to look for when purchasing and caring for them. With countless real-world examples, you’ll gain insight into natural, treated, and synthetic opals—as well as practical tips for wearing and storing them safely.

The Basic Course in Mineral Identification helps you improve your ability to identify and distinguish between minerals and gemstones. In this course, you’ll learn what minerals, gemstones, and crystals actually are, and you’ll receive an explanation of the key terms related to their shapes and properties. Using a handy step-by-step approach, you’ll learn to systematically examine the properties of minerals, such as their crystal shape, color, and hardness. You’ll do this using examples of several common minerals, as well as your own stones.

This mini-course, “Gem or Scam?”, will help you get better at identifying synthetic gemstones and minerals, imitations, and treatments. You’ll also learn what lies behind the many misleading names used for gemstones. You’ll receive tips on how to spot “scams,” so you can buy or sell gemstones with confidence and full knowledge of the facts.

Quartz is a common mineral that comes in a vast array of varieties and growth forms. The most well-known are, of course, the hexagonal prisms with a point at the top, but have you ever heard of the Tessin habit or artichoke quartz?

This Mini Course on Quartz Growth Forms will help you get better at recognizing and distinguishing between all the different growth forms. You’ll learn how quartz crystals grow and get an explanation of the key characteristics and names associated with the wide variety of forms.