While on a state visit to Sri Lanka in October 1981, the Queen was given this brooch by the Mayor of Colombo. The brooch is a spray of various types, colors, and cuts of precious and semi-precious stones to represent flowers, each with a gold stem and tied at the base with a gold bow. There are also two golden leaves at the base.
This large brooch has earned the honor of being worn for "regular duty", if you will - events outside of those specifically tied to Sri Lanka (a rather rare honor, when one considers the tremendous number of gifts the Queen has collected over the years which are rarely seen after they are accepted). In recent years in particular it has gained a few notable appearances, and it's nice to see her in some different colored stones and semi-precious stones too, for a change.