Fire opal, Mexico

Inclusions of hematite in feldspar (sunstone), India

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

Dendrites in agate

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

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

Inclusion of apatite in ruby from Tanzania

Partially etched diamond crystal

Two-phase inclusions in tourmaline from Namibia