Lot 492. Important diamond rivière, mid 19th century, property of the Estate of Mary, Duchess of Roxburghe. Estimate 245,000 — 340,000 CHF. Lot sold 586,000 CHF. Photo  Sotheby's.

Designed as a graduated row of forty-three collet-set cushion-shaped diamonds, on a similarly set clasp framed with single-cut diamonds, length approximately 465mm. 

Rivière [stream] is a term used to describe a necklace designed as a succession of gemstones individually set in simple collet or claw mounts without other ornamentation and often used as a synonym for a diamond set neck ornament. It is likely that the simple structure of the rivière was used for necklaces prior to the 18th century, but it was only in the second half of that century that rivières came to the forefront of jewellery design. These were formed of a line of gemstones of graduated size and mounted in closed collets.  By the turn of the century most rivières were set with gemstones mounted in open collets which remained the typical way of mounting until the end of the 19th century. A distinguishing feature of late 19th century rivières is the replacement of collets by claw settings.

Sotheby's. Magnificent Jewels and Noble Jewels, Genève, 12 mai 2015, 10:30 AM