This brooch has been owned by The Queen for many many years, it was the brooch worn for the official announcement of her engagement in 1947, and has been worn since.
It's origins and provenance are unknown.
Here is a very clear image of the brooch.
--Previous Message-- : Queen Elizabeth yesterday visited Perth, as : part of her Scottish visits for the Diamond : jubilee. : : Amon the events was a visit to Perth : College, which has many pictures on itīs : Flickr account: : : http://www.flickr.com/photos/perthcollegeuhi/sets/72157630449335482/ : : I donīt recognize this six-petal flower : brooch. Anyone? : : Also - the British Royal court has a blog : page about the Holyrood week, with stories : and pictures. : : http://www.royal.gov.uk/LatestNewsandDiary/Visitsandevents/HolyroodWeek2to6July2012.aspx : : Would any of you know the brooch worn with : the pink dress on July 4 for the Glasgow : visit? I cannot determine if itīs amethysts, : and am uncertain what flower it represents. :