Process for the production of a piece of jewellery

Abstract

A process for the production for a piece of jewellery by casting metal around a precious stone, wherein prior to the casting operation the precious stone is provided with a colouring agent-bearing coating and that during or after the application of the coating, the latter is subjected to an energetic treatment which causes those transformations of the coating which would occur without the energetic treatment upon casting the metal around the precious stone.

1 . A process for the production of a piece of jewellery by casting metal around a precious stone, characterised in that prior to the casting operation the precious stone is provided with a colouring agent-bearing coating and that during or after the application of the coating, the latter is subjected to an energetic treatment which causes those transformations of the coating which would occur without the energetic treatment upon casting the metal around the precious stone.  
     
     
         2 . A process according to  claim 1  characterised in that the energetic treatment includes heating to a temperature of between 950° C. and 1250° C. for a period of 1 to 20 minutes.  
     
     
         3 . A process according to  claim 2  characterised in that the energetic treatment includes a tempering operation at a temperature of between 700° and 800° C. for a period of at least one hour.  
     
     
         4 . A process according to  claim 1 , characterised in that the colouring agent-bearing coating is provided with a protective covering.  
     
     
         5 . A process according to  claim 4  characterised in that Li, Mg, Zn, B, Ce, Ti, Si, Zr or Al is contained in the covering.  
     
     
         6 . A process according to  claim 1  characterised in that a transitional layer is arranged between the precious stone and the coloured coating.  
     
     
         7 . A process according to  claim 1  characterised in that the rear side ( 2 ) of the precious stone ( 1 ) is protected by a ring ( 3 ) formed by the poured-in metal ( 4 ).  
     
     
         8 . A precious stone which is suitable for the production of an article of jewellery by pouring metal therearound according to  claim 1  characterised in that the precious stone is provided with a colouring agent-bearing coating of per se variable colour, which no longer substantially changes by virtue of an energetic treatment upon heating to a temperature below 1250° C.