A diamond necklace by designer Andrew Clunn smashed its estimate at Sotheby�s on Wednesday, selling for $4.1 million at the company�s New York auction.

The piece, set with 28 graduated, oval-shaped diamonds weighing more than 168 carats combined, achieved a price well above its $3 million high valuation at the June 9 Magnificent Jewels sale, Sotheby�s said. This established a new record for the designer at auction.

The necklace was part of a private collection of six jewels from the same anonymous seller. Three other pieces from the group also surpassed their presale valuations, including a Colombian emerald and diamond necklace by Harry Winston, which fetched $2.8 million. A 13.02-carat Burmese ruby ring by designer Carvin French went for $2.5 million against a $2 million upper estimate, while an emerald-cut, 23.59-carat, D-color, internally flawless diamond ring sold for $3 million. All six pieces sold, together garnering $15.4 million of the $37.5 million auction total.

Another highlight was the Sienna Star, a cut-cornered square step-cut, 73.11-carat, fancy-vivid-yellow, VS2-clarity diamond ring by designer Glenn Spiro, which beat its $3 million high estimate. The $3.4 million achieved was a record auction price for jewelry by Spiro, Sotheby�s noted.

Meanwhile, a cushion-cut, 25.29-carat Kashmir sapphire and diamond ring by Bulgari fetched $2.9 million, and a modified square brilliant-cut, 3.75-carat, fancy-intense-pink, VVS1-clarity diamond ring sold for $2 million, both within estimates.

The Magnificent Jewels sale featured advance online bidding and a live auction. Some 74% of bidders participated online, with 84% of the available lots receiving advance bids, Sotheby�s added. In total, the auction house sold 93% of items on offer. Of those, 65% exceeded their high estimates.

Image: The Andrew Clunn diamond necklace. (Sotheby�s)