Tiara russe (French). A type of tiara, derived from the Russian kokoshnik, in the form of a narrow band from which extend a series of closely-spaced, pointed, jewelled ornaments, sometimes of alternating lengths. When worn as a tiara, the ornaments projected upward, but the piece can also be worn as a necklace, unmounted from its frame and with the ornaments downward.
An example is owned by the British Royal Family, having been worn by Queen Alexandra and by Queen Mary who bequeathed it to Queen Elizabeth II. Another, made by Bapst for the Empress Eugénie, was among the French Crown Jewels sold in 1887.
From: An Illustrated Dictionary of Jewelry, autor: Harold Newman, publishers: Thames and Hudson