Stress fissure («sun spangle») in baltic amber

«Red fox agate» from Patagonia, Argentina

Dumortierite in rock crystal, Brazil, polarised light

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

Dendrites in agate

Two-phase inclusions in tourmaline from Namibia

Agate from Reichweiler, Germany

Partially etched diamond crystal

Two-phase inclusion in amethyst, Brazil