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

Stress fissure («sun spangle») in baltic amber

Agate from Reichweiler, Germany

Two-phase inclusions in tourmaline from Namibia

Structure in a healing fissure in topaz from Brazil

Fluid inclusions in quartz with bituminous daughter minerals, China

Epigenetic inclusion (probanly melanterite) in quartz, Brazil, parallel polarisers

Two-phase inclusions in sapphire, Sri Lanka

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