Two-phase inclusion in amethyst, Brazil

Colour zoning in ruby from Mong-Shu, Burma

Agate from Reichweiler, Germany

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

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

Fire opal, Mexico

Agate from Anzi, Maroc

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

Bubbles and swirls in moldavite (natural glass)