Grey Beluga caviar is the most prestigious of caviars, and whilst bigger isn’t always better, when it comes to Beluga the sturgeon’s larger size (it’s the third-biggest bony fish in the world) and therefore the size of its eggs are one of the key reasons it’s so prized. What’s more, Beluga sturgeon (huso huso) is indigenous to the Caspian Sea and there are strict rules regarding its over-fishing, which is what makes its roe so rare. Beluga sturgeon is only seen to have reached maturity at around 20 years old, again contributing to its scarcity – you can’t rush perfection.