(IDEX Online) - A 28.86-carat type IIa D-color diamond has sold for $2.1m, a world record high price for an online-only auction.Christie's say the near-flawless, VVS1-clarity emerald-cut stone (pictured) just exceeded a high estimate of $2m, attracting 31 bids during the two-week sale, which ended yesterday.The diamond's estimate in the Jewels Online sale was $1m to $2m."The sale of this exceptional stone established the record for a jewel sold in an online-only auction, demonstrating greater client confidence in Christie's digital ability and online sale platform," said Rahul Kadakia, Christie's International Head of Jewelry.Overall, the auction sold 100 per cent by value and 93 per cent by lot, with 64 percent of lots fetching above their high estimates.The next Christie's online jewelry sale, from July 3 to 13 features three pieces by designer Anna Hu, and will support healthcare workers fighting coronavirus.