Dendrites in agate

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

Fluid inclusions in quartz with bituminous daughter minerals, China

Inclusion of apatite in ruby from Tanzania

Two-phase inclusions in tourmaline from Namibia

Two-phase inclusion in amethyst, Brazil

Bubbles and swirls in moldavite (natural glass)

Inclusions of gilalite aggregates in rock crystal from Brazil

Fire opal, Mexico