Oud - The Liquid Gold of Perfumery 

What is Oud? Oud, also known as Oudh, Agarwood, or "liquid gold," is one of the rarest and most expensive perfume ingredients in the world. It is a fragrant resin that forms in the heartwood of Aquilaria and Gyrinops trees when they become infected with a specific mold (Phialophora parasitica). The tree reacts by producing a dark, aromatic resin, which gives oud its rich, complex scent.