Diamonds might be a girl's best friend, but they don't come cheap.

A flawless Ontario diamond just sold for a whopping $20.9 million in an online Hong Kong auction on Monday. 

The ultra-rare rock, which is 102.39 carats, was discovered in the now-closed Victor Mine in Northern Ontario.

Editor's Choice: Ontario Driver Was Racing A Truck Down The 401 With A Guy Chilling In The Back (PHOTO)

$20.9 Millon Ontario diamond sold

Before its sale, the white diamond was boasted as being amongst the best in the world.

It was original discovered as a 271-carat rough in 2018, before being polished down to the beautiful shape it is today. 

"This stunning diamond is the best of the best when it comes to exceptional white diamonds and it is difficult to overstate its rarity and beauty," said Gary Schuler, Worldwide Chairman of Jewelry.  

According to a report by CTV News, diamonds are now being swept up as alternative investment opportunities during the pandemic.