Dumortierite in rock crystal, Brazil, polarised light

Inclusions of rock crystal and rutile needles in quartz, Brazil, polarised light

Two-phase inclusions in sapphire, Sri Lanka

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

Two-phase inclusions in tourmaline from Namibia

Inclusions of hematite in feldspar (sunstone), India

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

Agate from Reichweiler, Germany

Dendrites in agate