Can you guess what are the most expensive things that exist in the world? Are they cars, or jewellery? Read on as we look at the world's most expensive things and their staggering prices.

Narrator: High-quality black opal can cost over $10,000 per carat, making it one of the world's most expensive gemstones ... You can put the thing away for a week, pick it out and look at it ...

They're also one of the most expensive nuts in the world, selling for upwards of $117 per kilogram. So what makes them so special? And why are they so expensive? More from Retail Pine nuts have ...