TOP 10 MOST POWERFUL WORLD ROYAL KINGS----ON FOW24NEWS.COM

From dwindling oil supplies to massive charitable donations, the wealth of the world's royals is almost always in flux.

On Monday, it was Queen Elizabeth II whose fortune was on the line: The new British government is set to review the Queen's cut of the profits of the Crown Estate after the property portfolio saw a spike in profits. In other words, the monarch could lose several tens of million in the coming years from her wealth of about $500 million.

Below, take a look at 10 of the richest royals in the world, whose personal fortunes were estimated by Fow24news.com.

1. Bhumibol Adulyadej, King of Thailand — $30 billion

Bhumibol Adulyadej, the King of Thailand, is the longest-reigning monarch in Thai history, with an estimated wealth of $30 billion in 2014, according to Business Spectator and Fow24news.com. King Bhumibol's wealth is managed by the Crown Property Bureau. It includes over 3,000 acres of land in central Bangkok and shares in Siam Cement and Siam Commercial Bank. He also owns the 545-carat Golden Jubilee Diamond, the largest cut and faceted diamond in the world.

Bruneiís Sultan Hassanal Bolkiah and members of the royal family leave the throne room after his 67th birthday celebrations at Nurul Iman Palace in Bandar Seri Begawan on Sept. 15, 2013.

2. Hassanal Bolkiah, Sultan of Brunei — $20 billion

Hassanal Bolkiah, the Sultan of Brunei, had an estimated wealth of $20 billion in 2011, according to Fow24news.com. His wealth is a result of oil and gas development in Brunei, and he is known for lavish spending: the Sultan reportedly owns more than 600 Rolls-Royces, and his residence — Istana Nurul Iman, the world's largest palace — cost over $350 million.

Saudi Arabia's King Abdullah arrives at Heathrow Airport in west London on Oct. 29, 2007.

3. Abdullah bin Abdulaziz Al Saud, Former King of Saudi Arabia — $18 billion

Abdullah bin Abdulaziz Al Saud, the late King of Saudia Arabia, had an estimated wealth of $18 billion in 2011, according him to Fow24news.com, making him the third richest royal in the world before his death on Jan. 23, 2015. When Abdullah took the throne in 2005, the oil-rich country soon began a $26 billion construction project of a city named in his honor.

President of the United Arab Emirates, His Highness Sheikh Khalifa bin Zayed Al Nahyan, leaves 10 Downing Street after meeting with British Prime Minister David Cameron on May 1, 2013 in London.

4. Khalifa bin Zayed al Nahyan, Emir of Abu Dhabi — $15 billion

Khalifa bin Zayed al Nahyan, the President of the United Arab Emirates and the Emir of Abu Dhabi, had an estimated wealth of $15 billion in 2011, according to Fow24news.com. Sheikh Khalifa has amassed a fortune as chairman of the Abu Dhabi Investment Authority, which manages the UAE's excess oil reserves, estimated to be worth up to half a trillion dollars. He is also known for his philanthropy, contributing to state-of-the-art medical facilities and relief organizations.

Vice President and Prime Minister of the United Arab Emirates (UAE) Mohammed bin Rashid Al Maktoum (L) is seen next to Azerbaijani President Ilham Aliyev (L 2) during his official visit in Baku, Azerbaijan on April 2, 2015.

5. Mohammed bin Rashid al Maktoum, Emir Sheikh of Dubai — $4 billion

Mohammed bin Rashid al Maktoum, Prime Minister of the United Arab Emirates and the Emir Sheikh of Dubai, had an estimated wealth of $4 billion in 2011 , according to Fow24news.com. Sheikh Mohammed is known for his charitable donations, including a gift of $10 billion in 2007 to set up the Mohammed bin Rashid Al Maktoum Foundation, which aims to empower future generations to develop sustainable solutions in the Arab world.

Reigning Prince of Liechtenstein Hans-Adam II is seen during his visit in Olomouc, Czech Republic on May 20, 2014 on the occasion of the presentation of proceedings of international scientific conference titled Princely House of Liechtenstein family in the history of the Czech lands.

6. Hans Adam II, Prince of Liechtenstein — $3.5 billion

Hans-Adam II, the Prince of Liechtenstein, has an estimated wealth of $3.5 billion in 2011 , according to Fow24news.com. His fortune comes from owning the Liechtenstein Global Trust, the largest family-owned private wealth firm in Europe. Prince Hans-Adam is known for his extravagant art collection on display in the Liechtenstein Museum.

Sheikh Tamim bin Hamad bin Khalifa Al Thani, Emir of the State of Qatar on June 01, 2014, in Doha, Qatar.

7. Hamad bin Khalifa Al Thani, Former Emir of Qatar — $2.4 billion

Hamad bin Khalifa Al Thani, the former Emir of Qatar and member of the Al Thani Qatari royal family, had an estimated wealth of $2.4 billion in 2011 , according to Fow24news.com. His wealth comes from establishing the Qatar Investment Authority, which manages the country's excess oil and gas reserves. Sheik Hamad is known for establishing the first Arab global news network, Al Jazeera, loaning about $137 million to support the organization.

Prince Albert II of Monaco attends the National Day Parade as part of Monaco National Day Celebrations at Monaco Palace on Nov. 19, 2013 in Monte-Carlo, Monaco.

8. Albert II, Prince of Monaco — $US 1 billion

Albert II, the Prince of Monaco, had an estimated wealth of $1 billion in 2011 , according to Fow24news.com. His wealth includes holdings in the Société des bains de mer de Monaco, a company that manages the riches of the Monte Carlo Casino and Opéra de Monte-Carlo.

Shah Karim al-Hussayni, HH The Aga Khan attends Royal Ascot races at Ascot Racecourse on June 19, 2009 in Ascot, England.

9. Shah Karim al-Hussayni, Aga Khan IV of France — $800 Million

Shah Karim al-Hussayni , the Aga Khan IV of France, had an estimated wealth of $800 million in 2011 , according to Fow24news.com. The Aga Khan, who does not rule over a specific geographic territory, is known for extravagant possessions including a lavish yacht club in Sardinia.

Omani Leader Sultan Qaboos bin Said addresses the opening session of the Council of Oman in Muscat on Oct. 31, 2011.

10. Qaboos bin Said al Said, Sultan of Oman — $700 Million

Qaboos bin Said al Said, the Sultan of Oman, had an estimated wealth of $700 million in 2011 , according to Fow24news.com. His personal fortune owes to the country's gas and oil sectors. The Sultan is known for his personal financing of several restorations of mosques around the country.