Spinel crystal in dolomite marble, Burma

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

Structure in a healing fissure in topaz from Brazil

Two-phase inclusions in tourmaline from Namibia

Twin-crystal of chrysoberyl

Fire opal, Mexico

Stress fissure («sun spangle») in baltic amber

Inclusions of rock crystal and rutile needles in quartz, Brazil, polarised light

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