Alfred Thielemann, turquoise brooch

Alfred Thielemann, a diamond and turquoise brooch, Russia, circa 1905, designed as a whiplash motif set with rose-cut diamonds and a circular-cut diamond, to a drop-shaped motif set with a cabochon turquoise within a border of rose-cut diamonds, mounted in silver on gold, length 3.3cm, Russian assay mark for gold, assayer initials AP for Alexander Romanov (1904-12), workmaker's mark AT for Alfred Thielemann (1870-1910), case stamped Walter & Bull