As perhaps the most famous engagement ring on the planet, Kate Middleton‘s sapphire and diamond beauty is getting a hefty new price tag to reflect its irreplaceable value. Prince Charles originally purchased the 12-carat rock in 1981 for Diana, Princess of Wales, for an already impressive £28,000, or the equivalent of roughly $47,000.
Thirty-three years later, the glittering sapphire stone has taken up residence on a new member of the royal family—and with that added significance, a reported new value of £300,000 (or more than $505,000)—ten times its original value.
By any standards, royal or not, that’s a lot of dough—even for a priceless artifact such as Middleton’s engagement ring. To put it into perspective, however, the value of Kim Kardashian‘s rock could be valued at up to six times that much. Six. Some jewelry experts estimate that Kardashian’s absurdly enormous 15-carat gem, created by Kanye West and jewelry designer Lorraine Schwartz, may be worth upwards of $3 million.