A Strikingly Beautiful Gold Mounted Carved Boulder Opal Antique Russian Miniature Egg Pendant. This highly unusual egg was made in St. Petersburg between 1908 and 1917 by jeweler W. Warburton. Jewelry by Warburton is extremely rare today. Clearly, this gold mounted carved egg was influenced by Warburton's neighbor - Peter Carl Faberge, whose shop was at B. Morskaia No. 16, and after 1900 - at B. Morskaia No.24.