Paste

Paste in jewelry refers to heavy flint glass which is used to make imitation gemstones. Such glasses have a high lead content, resulting in a high refractive index, allowing the material to achieve a brilliancy and fire approaching that of real gemstones. Metallic oxides are added so that different colours can be reproduced, matching that of the gemstone being mimicked. The material is called paste because the components of the mixture are mixed when wet to ensure a thorough and even distribution. Paste gemstones were, in the 18th and 19th centuries, considered an art form and apparently popular and fashionable. An expert could easily detect a paste imitation. A common criminal might not, however, notice it so quickly, especially if he or she is in a hurry.

Use of paste as a plot device in the stories of Agatha Christie

 * The Adventure of 'The Western Star' - a paste imitation was made for Lady Maude Yardly. She had given her real "Star of the East" diamond to a blackmailer.
 * The Adventure of the Christmas Pudding - Poirot had a paste ruby made. The thief ran off with the paste imitation.
 * The Disappearance of Mr Davenheim - Mr Davenheim stole from his wife's jewels, replacing them with paste copies over a period of time. He then disappeared.
 * The Veiled Lady - As part of a clever jewel robbery scheme, a jewel shop is robbed. Some "helpful" passers-by by tackle him. The robber is brought to the police station where the robber's loot is found to be paste. The helpful passer-by had switched the real jewels for paste ones.
 * The Case of the Distressed Lady - A woman comes to Parker Pyne to ask him for help to replace a paste copy of a jewel with the real thing.
 * Have You Got Everything You Want? - Elsie Jeffries has her jewels stolen while travelling on the Orient Express. The jewels are later revealed to be paste copies.
 * The Oracle at Delphi - paste copies of jewels are used in an elaborate kidnapping/jewel theft scheme.