In the Middle East, they take their oud very seriously but internationally, it has only caught on in a big way in the last few years. It is derived from the tropical agar tree, which is thought to originate in Assam in India. When the tree is infected by a mould known as Phialophora parasitica, it reacts by producing a dense, dark and fragrant resin to protect itself. It is the resin-embedded heartwood of the tree that is the source of oud.

The trees are grown throughout south-east Asia, India and Bangladesh and agarwood is said to be the most expensive timber in the world -- indeed, one of the most expensive of all natural raw ingredients.

Part of the reason for the cost is that the agar tree is now registered by CITES as a potentially threatened species -- not surprisingly when the global agarwood market is thought to be worth over ?5 billion annually.

The scent itself varies considerably depending on the wood used, where the tree was grown and whether the tree itself was cultivated or naturally infected. The fragrance is -- unsurprisingly -- described as warm, woody with a slight hint of damp rot, while some varieties are smoky and sweet. It can be very potent, so not one for the faint-hearted, but if there's any men's perfume that can last from the boardroom to the bedroom, it's this.

12 best oud fragrances for men

This article originally appeared on gq-magazine.co.uk.