The Natural History department conducts three auctions per year, firmly establishing Bonhams as the forerunner in the field internationally. An extraordinarily wide range of categories are offered, including: mineral specimens; fossils, including dinosauria, petrified wood, amber and ammolite; unmounted faceted gemstones, including rare phenomenal gemstones; gold; meteorites; lapidary, archaeological stone artefacts; mounts and animal, plant, insect and shell specimens, pearls and coral, and natural history-related decor and curiosities.

With consignments culled from private collections, palaeontologists, fossil preparators, quarry and mine owners, the auctions are successful in providing specimens that are fresh to the market.