LONDON (REUTERS) - "The Pink Raj", an intense pink diamond described by experts as the world's largest, is expected to fetch up to US$30 million (S$40.5 million) when it is auctioned in Geneva next month.

The stone, which weighs just over 37 carats, was displayed by auction house Sotheby's in London this week.

"It is a wonderful shape. It is a cushion modified diamond, with a lot of brilliance, a lot of facets, when you move it around and sort of have it on your finger," Sotheby's senior jewellery specialist Daniela Mascetti told Reuters.

The rough diamond was mined in 2015 and is being auctioned by an anonymous owner. Previous sales for smaller pink diamonds have yielded more than $1 million per carat at auction.

A 24.78 carat intense pink diamond sold for more than US$46 million - a record price per carat for pink diamonds - in November 2010 in Geneva.