Opaline glass, which should more correctly be termed 'cristal d'opale', is formed from a type of lead crystal which is then coloured by the addition of other substances.
'Cristal d'opale' first appeared in the Empire period when the celebrated Baccarat factory was established. Baccarat rivalled and rapidly eclipsed the output of the English and Bohemian manufacturers, which until then had dominated the production of crystal glass. The taste for such coloured opalines was particularly marked in the Restauration period. The Journal des Dames et des Modes in January 1824 for instance remarked that 'On a donn aux dames, en cadeau de Jour de l'An, beaucoup de cristaux colorés en blanc laiteux dit opale; en rose dit hortensia, en bleu dit turquoise...' (S. Faniel ed., Le Dix-Neuvième Siècle Français, Paris, 1957, p. 126).