One of the world’s largest diamonds, a pear-shaped 110.3-carat yellow rock, will go under the hammer in Geneva in November expecting to fetch about $15 million.

The Sun-Drop diamond, discovered in South Africa last year, is billed by Sotheby’s as the “world’s largest known pear-shaped fancy vivid yellow diamond“.

“This stone has immense presence and is truly stunning. It is also one of the largest diamonds ever to have appeared at auction,” Sotheby’s Switzerland co-chairman David Bennett told a news conference in Hong Kong.

A massive uncut emerald on exhibit in Colombia’s capital is being touted by its owners as the biggest in the world, officials said Saturday.

The 11,000-karat raw green gem weighs in at 2.27 kilos (almost five pounds) and is on show in Bogota 12 years after it was mined in Muzo, in the South American nation’s emerald country in Boyaca province.

“It is priceless,” Santiago Soto, spokesman for the Minergemas 2011 gem industry trade fair under way in Bogota, said of the stone owned by the firm Coexminas.

A rare pink diamond that is regarded as one of the most desirable and beautiful in the world was sold for a record 46.16 million dollars on Tuesday.

Sotheby’s had valued the 24.78 carat Fancy Intense Pink diamond mounted on a ring at 27 million to 38 million dollars ahead of the sale in a luxury lakeside hotel.

But intense bidding wiped out the record of over 24 million dollars set during an auction in December 2008 in the sale of a grey-blue diamond Wittelsbach.

An exceptinally rare pink stone is set to break the record for being the world’s most expensive diamond ever.

The pink stone is estimated to be worth $27-38 million when it goes under the hammer on November 16 at Sotheby’s in Geneva

It is classified as ‘fancy intense pink’ – the most perfect pink colour – by the Gemological Institute of America, and is set between shield-shaped diamond shoulders on a silver ring.

Petra Diamonds Limited announced that the 507 carat Cullinan Heritage sold for US $35.3 million, the highest sale price on record for a rough diamond.

The diamond was sold on tender in South Africa and was purchased by Hong Kong-based Chow Tai Fook Chow Tai Fook Jewellery Company .

The Cullinan Heritage was recovered in September 2009 from Petra’s Cullinan mine in South Africa.

At 507.5 carats it is the nineteenth largest gem diamond ever discovered.

Gemfields has officially announced the discovery of an absolutely enormous rough emerald earlier this month in their Kagem mine in Zambia.

The emerald has been named “Insofu,” which means ‘elephant,’ by the indigenous Bemba people to both honor its size and pay tribute to the World Land Trust’s “Wild Lands Elephant Corridor Project.”

The emerald weighs in at 6,225 carats and is currently under the scrutiny of experts to determine its value and evaluate what possible futures it might have.