Flawless 100 carat diamond up for auction at Sotheby's

Sotheby's in New York is to auction what it says is a 'flawless' 100 carat diamond. A diamond without a single imperfection, may be worth $25m.

There has been a recent spate of record-breaking sales in rare gems. Sotheby's says the high price tags are not putting people off.

Some see diamonds as a safer bet for their millions than in the investment market.

Catharina Moh reports.