This flower brooch is in the form of a spray of millet (sometimes called sorghum), a crop that is abundant in Botswana. It features 11 pear shaped diamonds to create the heads of the millet, with simple crafted gold for the stem and leaves.
The President of Botswana, Festus Mogae, presented the piece to The Queen in 2007 at the Commonwealth Heads of Government Meeting. The brooch was exhibited in 2009, From Her Majesty’s Jewel Vault points out, giving us a great up close with the piece. You can read more about that here.