Lovebird: a jewelled purpurin egg pendant, probably St Petersburg, circa 1900

 A rare form of glass, purpurine was used in a select number of works by Fabergé and was described by Henry Bainbridge, manager of Fabergé's London branch, as:

‘And there is another substance, the work of man, not nature, but none the worse for that, at any rate from the point of rarity, for its creator is dead and it can never be made again as his secret died with him. I refer to the vitreous substance called purpurine. It was the invention of a workman called Petouchoff of the Imperial Glass Factory in St. Petersburg. The material has much the nature of obsidian, is of that wonderful red colour named by the French sang de boeuf, and is very heavy, having gold in its composition.’ (H.Bainbridge, Peter Carl Fabergé: His Life and Works, London, 1949, p. 54) 

According to Kenneth Snowman, the Fabergé workshops seemed to have the exclusive use of this distinctive material created by the crystallization of lead chromate in a glass matrix (K. Snowman, The Art of Carl Fabergé, London, 1962, p. 59).