Two-phase inclusion in amethyst, Brazil

Structure in a healing fissure in topaz from Brazil

Dendrites in agate

Agate from Reichweiler, Germany

Inclusions of anatase crystal and rutile fibres in rock crystal from Brazil

Agate from Anzi, Maroc

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

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

Spinel crystal in dolomite marble, Burma