This excerpt from Ruby & Sapphire: A Gemologist's Guide (2017) details the ruby and sapphire deposits of Madagascar. Since the mid-1990s, Madagascar has become one of the world's most important sources.

A discussion of the literature of jade, with particular emphasis on the most collectable books covering both Chinese jade and jade around the world.

27 February 2019: Sapphires heated with high temperatures and low pressures (~1kbar) first entered the market in 2009, becoming more common since 2016. This article examines the process in detail and looks at the question of whether a separate disclosure is needed for the treatment.

The history of the Lao sapphire mines at Ban Huay Xai is detailed, along with modern mining by Hong Kong based Sino Resources Mining Corp. Ltd. from 2006–2012.

A Burmese sapphire shows a celestial scene both externally and internally.

An included calcite crystal within an unheated Burmese ruby displays dramatic twinning planes.

Surface-reaching growth tubes in a sapphire provide insight into the gem’s origin and treatment history.

A ruby’s surface-reaching cavity is filled with red oil.

The optical properties of crystals are intimately related to their crystal structures. This article examines the precise relationship between optic character and sign and crystal structure.

At the Lotus Gemology laboratory in Bangkok, we often get parcels of relatively uniform stones. But sometimes it is in this routine testing that we uncover surprises.