This is quite an unusual and rare early Victorian small kilt pin or brooch in the shape of a dirk.
Instead of the usual silver, the metal is gold, and it is set with, what I believe to be, all Scottish gemstones. The top of the handle looks to be a cairngorm or citrine, the handles of the two smaller knives amethysts and the body of the dirk a dark green jade like stone.
The brooch is 5.7cm long, the two amethysts are ca. 4mm long and the Cairngorm at the top is 9mm long. The metal is not stamped, but tests as solid 9 carat gold.
The old-fashioned catch indicates that this brooch is Victorian, I would think from ca. 1850 and is likely to have been made by a provincial jeweller.
It comes in its original antique box, which looks a bit scuffed on the outside, but is structurally totally sound and really nice to have.
The brooch weighs 4.96 grams and is in excellent overall condition.