Changes create greater purchasing flexibility for non-Sightholders.
Team went on fact-finding trip to emerald and tourmaline mining areas.
Rough ruby and corundum gems sold in Singapore for US$18 per carat.
Mobile Buyer Guide app offers visitors an interactive exhibitor guide.
The pear-shaped diamond was purchased by Harry Winston for £14m.
Company reports unprecedented bidding for white and fancy colours.
Company says stone was placed in possession of new owner in 2008.