​How wealthy is Queen Elizabeth? Not as rich as you'd think

Just like the British empire, the fortunes of its longest-reigning monarch aren't what they used to be.

Queen Elizabeth II, who on Wednesday surpassed Queen Victoria as the longest-reigning British head of state, has ruled during an era of unprecedented wealth creation. Since she took the throne in 1952, modern portfolio theory was invented; companies including Berkshire Hathaway (BRK.A) to Apple (AAPL) were founded; and new economic super-powers such as China emerged.

Much of the monarch's portfolio, however, is tied to inherited wealth in the form of real estate and jewels that, while providing a hedge against inflation, haven't necessarily kept up with the surging fortunes of the super-rich. Queen Elizabeth's personal fortune stands at about $425 million, according to an estimate from the Bloomberg Billionaires Index.

While that's nothing to sneeze at, it pales in comparison to the riches of Bill Gates, who ranks as the world's wealthiest man with a net worth of $79.1 billion, or Christy Walton, the world's wealthiest woman, who is worth $34.2 billion. Both of their fortunes are tied to the creation of U.S. businesses that ultimately sold shares to the public, providing liquidity and the ability to diversify their assets.

The details of Queen Elizabeth's personal fortune aren't disclosed by the monarchy, but Bloomberg estimates her estate as including $160 million of assets inherited from her mother; $110 million in personal property; a $75 million stamp collection; and the $10 million Royal Stud.

Her property includes the Balmoral and Sandringham estates, the 3,000-carat Cullinan diamond, and an art collection. Because much of her fortune is held in trust, she has little flexibility in rebalancing property into equities or more liquid investments, according to The Financial Times.

On the other hand, Queen Elizabeth's value to Britain has seen the type of growth that would make the richest hedge-fund manager smile.

The monarchy is now worth $87 billion to Britain, according to brand consultancy Brand Finance. That represents a jump of 30 percent from 2012, when the company estimated the monarchy's value at $67 billion. In 2015, it estimates the monarchy will add $1.8 billion to the country's economy.

One driver of that increased value has been the emergence of a new generation of royals, said Robert Haigh, marketing and communications director for Brand Finance.

"Over those three years Kate has really established herself as a major draw and 'marketing tool' for the monarchy and Britain as a whole," Haigh wrote in an email, referring to Catherine, the Duchess of Cambridge. Her children with husband Prince William, George and Charlotte, "have both been born in that time. They have huge financial clout even if they're unaware of it as demand for the clothes they wear and toys and other products they use is vast."

The brand value doesn't include the personal wealth of the queen, Haigh noted.

"We wouldn't describe [her personal wealth] as part of the institution of the monarchy," he noted. "Having said that though, it is thought that she is very patriotic with her investments. In addition to a portfolio of generally British properties such as Balmoral and Sandringham (which employ groundskeepers and countless other staff) she has invested in largely British blue-chips, so is helping to support the British industry."

That estimate is based on the lift to the economy from tourism and from price premiums given to brands with Royal Warrants (the "By Appointment to HM The Queen" logos seen on everything from Cadbury chocolates to Burberry), as well as funds generated by the Crown Estate.

The Crown Estate, which isn't the personal property of the Queen, sends all of its profit to Britain's Treasury. It's been having a very good year, with profits rising almost 7 percent for its most recent fiscal year, which ended in March.