Epigenetic inclusion (probanly melanterite) in quartz, Brazil, parallel polarisers

Dumortierite in rock crystal, Brazil, polarised light

Fire opal, Mexico

Stress fissure («sun spangle») in baltic amber

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

Two-phase inclusions in sapphire, Sri Lanka

Inclusions of fossil plant debris in opal from Wollo, Ethiopia

Structure in a healing fissure in topaz from Brazil

Colour zoning in ruby from Mong-Shu, Burma