1. Untreated coloured gemstones
About 90 per cent of gemstones are heated to improve their colour or clarity. Some of the rarest untreated coloured gemstones are Kashmir sapphires, so it’s likely these will be very popular at auction this year.
2. Pink diamonds
Less than 0.1 per cent of diamonds mined worldwide are pink and they are only found in certain areas, such as the famous Argyle mines in Kimberley, Western Australia. Last year, the Argyle mines closed for good, and prices for pink diamonds reportedly shot up 40 per cent.