Being worth your weight in gold is not necessarily such a strong accolade. Despite the popular saying, there are several substances that are pound-for-pound much pricier than the yellow metal. Measured by the gram, here are some of the most valuable substances in the world.

The Telegraph

1. Saffron: £10 per gram
The most expensive spice in the world, saffron costs between £5 and £10 per gram at the supermarket. The spice is so dear because the process is labour intensive. Each flower produces just a few stigmas, which need to be hand-picked and dried before used with food. It can take around 150 flowers to produce a gram of saffron.

2. Iranian beluga caviar: £20 per gram
The eggs from this rare sturgeon generally cost about £20 per gram and have been dubbed by the Guinness World Records as the most expensive food in the world.

3. Platinum: £23 per gram
In 1976, the Recording Industry Association of America introduced the platinum certification for records that sold more than one million units. However, at £23,144.63 per kg, or just over £23 per gram, platinum is currently less valuable than gold.

4. Gold: £28 per gram

Gold has slipped from its 2011 high of £37.31 over recent years, but a rebound this year has taken the price back up from its £22.37 low in August 2015.

5. Heroin: £55 per gram
One hit of heroin would likely be anywhere from 10 mg to a few hundreds mgs. But by the gram, heroin is among the more expensive drugs, costing around £55. That compares to £46 for a gram of cocaine, £39 for a gram of ecstasy and £13 for a gram of speed.

6. Rhino horn: £69 per gram
Rhino horns can fetch up to $100,000 per kg, or £69 per gram. Poaching has seen a resurgence since 2008, after a rumour spread that rhino horn powder had cured a Vietnamese politician of cancer and amid growing wealth in the Southeast Asian country.

7. Gold powder: £200 per gram
Iranian beluga caviar might be the most expensive food in the world, but it isn’t the costliest thing you can put in your mouth. Gold leaf, which is also used for gilding, decoration and conducting electricity, is said to be the most valuable edible substance in the world. A gram of 24-carat gold leaf flakes can cost around £68 – although a gram of even finer gold powder can be costlier, going for £200 per gram.

8. White truffle: £222 per gram
In 2010, the most expensive Alba white truffle ever sold, weighing 1.3kg, went to Macau billionaire Stanley Ho for $417,200, meaning he paid $320.92 per gram. However, presumably less superior Alba white truffles can be bought for around £3 per gram.

9. Venom: £935 per gram
Animal venoms have several medicinal uses, from relieving pain to treating cancer, and even reversing the effects of a poisonous bite. A gram of snake venom can fetch £263, while scorpion poison goes for £415. The priciest spider venom costs £935 per gram

10. LSD: £2,085 per gram
Lysergic acid diethylamide (LSD), also known as acid, is a psychedelic drug known for its psychological effects. This may include altered awareness of the surroundings, perceptions, and feelings as well as sensations and images that seem real though they are not.

The most common form of LSD is a small square of paper that melts on the tongue. At around $5 for a hit of acid, that adds up. A gram of LSD in crystal form can cost around $3,000.