Aigrette:  jeweled hair ornament that was once used to hold feathers but now they are usually worn without

Bandeau:   a headband or low tiara sometimes worn across the forehead

Cabochon:  a polished stone that is rounded instead of being cut with facets

Circlet:  goes all the way around the head

Diadem:   often used interchangeably with tiara

En Tremblant:  French for 'to tremble' meaning that the jewel is set on a wire so that it moves and catches the light

Kokoshnik:  a traditional Russian girls headdress and its shape is sometimes imitated by tiaras; women of the Russian imperial family often wore their tiaras or other jewels sewn on a fabric kokoshnik

Parure:  a matching set of jewels

Provenance:  origin and history