(IDEX Online) - A 12.11-carat blue diamond ring could fetch $12.25m as the highlight of the first live Christie's auction since lockdown.The marquise-cut stone, described as an internally flawless fancy intense blue, will go under the hammer on 9 July at the Magnificent Jewels Auction in Hong Kong, which was postponed from 2 June.Sales have been taking place online since lockdown was introduced in March. Restrictions are now being lifted and schools re-opened yesterday.The blue diamond ring (pictured) is estimated to fetch between $8.38m and $12.25m.Other lots include a 6.06-carat Burmese 'Pigeon's Blood' ruby and diamond ring ($830,000 to $1.23m) and a diamond necklace featuring 12.81 and 6.50-carat Kashmir sapphires ($770,000 to $1.03m).