1 1 2 Pearls. 



and the consecutive layers vary in brightness, colour 

 and perfection. The most highly prized Pearls are 

 quite spherical, and it is evident from their shape 

 that these must have been formed free in the 

 mantle or in the soft tissues of the mollusc, and 

 not cemented to the shell. Some Pearls shew defects, 

 caused apparently by the contact of new foreign 

 substances, organic or inorganic, such as grit or a 

 film of weed ; and in some cases it requires a number 

 of layers to completely hide these defects. Thus, 

 every new layer secreted, changes the value of the 

 Pearl. 



When a Pearl that has been cut from the shell 

 presents a hemispherical surface, it is sometimes 

 called a prrle bonton; such a Pearl is flat on one 

 side, and rounded or convex on the other. If a 

 solid Pearl has an irregular shape, having grown 

 over a rough object, it is known to jewellers as 

 baroque pearl. Sometimes the warty Pearls are hollow, 

 and pass under the name of coq de perle. 



An attempt has been already made in a former 

 chapter to explain how the Pearl-oyster rids itself 

 of any foreign substance that may get into its shell, 

 such as a stone or piece of wood : and in now dealing 

 with the subject of real Pearls, the same explanation 

 of the formation of " blisters " must be borne in 



