Two-phase inclusions in tourmaline from Namibia

Dumortierite in rock crystal, Brazil, polarised light

Two-phase inclusions in sapphire, Sri Lanka

Inclusions of rutile (dark crystal and fine needles) and clusters of zircon grains in umbalite garnet, Tanzania

Natural etching structure on a crystal face of diamond (trigons), polarised light

Agate from Reichweiler, Germany

Two-phase inclusion in amethyst, Brazil

Inclusions of hematite in aquamarine, Tanzania

Inclusions of fossil plant debris in opal from Wollo, Ethiopia