Nature's handy work in the making of gems is no less dazzling than their
appearance. Contained within gems are clues to the prehistory of our planet.
Tourmaline records mountain building episodes, the chemistry of magma chambers
and the composition of fluids that flow through the Earth's crust.
Rapidly changing pressure, temperature and compositional conditions
are forever encased in the composition of a single tourmaline. In contrast,
diamonds provide insights into the chemistry and composition of the
Earth's mantle and the unique conditions that occur
at depths of 120 - 190 km below the surface. Diamonds record a fascinating
history of creation and survival through ca. 160 km of high speed
transport to the surface. Each diamond that adorns is at least 40 million years old,
and may be as old as 3.5 billion years! This presentation will
highlight the genesis of  diamonds and tourmaline,  their transportation to the surface,
the environmental conditions that they represent  and their
survival though the millenia to ultimately give us some of the
most prized gemstones on Earth.

View more fabulous gemstones at the nation's museum

align="center"