Which spice is the most expensive in the world, often called “red gold”?

Saffron

Saffron is recognized as the most expensive spice in the world, due to its extremely labor-intensive harvesting process. Each Crocus sativus flower produces only three saffron stigmas, which must be handpicked at sunrise to preserve their quality and aroma. It takes about 150,000 flowers to produce one kilogram of dry saffron, explaining its high price. Besides its culinary use to flavor and color dishes like paella and Milanese risotto, saffron is also valued for its medicinal properties, including its anti-inflammatory effects and its ability to improve mood.