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Precious stones, gems and rocks

Precious, semi-precious stones, and rocks belong to the mineral reign. Here again, the role of CARAA is to determine the use of the most efficient analysis method regarding the object (value, size) and sampling possibilities.


Choosing the right techniques


Fully understanding a rock or mineral can be complex. It is very rare that a single technique answers all the problems concerning a mineral; for example: what is the reason of the yellow color of a diamond? Is it natural or due to irradiation or heating induced by man? What are the inclusions present in it ?

A role of expertise at CARAA


Confirming or disproving the composition of a gem or a crystal is the base of its authentication. Common examples are the differentiation between diamond and its substitutes (zircon -ZrO2- or SiC -moissanite-), an amethyst from a colored glass or a rock crystal (quartz) from an uncolored glass (see the picture of the crystal rock Aztec skull below).

Determining the provenance


The geographic origin of a gemstone or mineral can be determined through the analysis of the natural inclusions incorporated during their geological formation. The geographical location of many types of marble is another example of possible analysis.





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  • Antic Roman gem.
  • 18-19<sup>th</sup> c. gem reproduction in the frame of a non-invasive analyses project,© The J. Paul Getty Trust. All rights reserved.
  • 18-19<sup>th</sup> c. gem reproduction in the frame of a non-invasive analyses project,© The J. Paul Getty Trust. All rights reserved.
  • 18-19<sup>th</sup> c. gem reproduction in the frame of a non-invasive analyses project,© The J. Paul Getty Trust. All rights reserved.
  • 18-19<sup>th</sup> c. gem reproduction in the frame of a non-invasive analyses project,© The J. Paul Getty Trust. All rights reserved.
  • 18-19<sup>th</sup> c. gem reproduction in the frame of a non-invasive analyses project,© The J. Paul Getty Trust. All rights reserved.
  • 18-19<sup>th</sup> c. gem reproduction in the frame of a non-invasive analyses project, (JP Getty Museum).
  • 19<sup>th</sup> c. cameo (Priv. Coll.).
  • Antic gem mounted in a ring and revealing mineral inclusions,© The J. Paul Getty Trust. All rights reserved.
  • Antic Roman gem, detail of mineral inclusions.
  • Antic Roman gem,© The J. Paul Getty Trust. All rights reserved.
  • Precious and semi-precious stones submitted for expertise analyses.
  • Rough diamond collection submitted for expertise analyses.
  • Amethyst and topaz, precious and semi-precious stones submitted for expertise analyses.
  • Ambers and insects inclusions.
  • 17<sup>th</sup> c. gilded mirror and precious stones (diamonds, emeralds, rubies, ...), detail.
  • 17<sup>th</sup> c. gilded mirror and precious stones (diamonds, emeralds, rubies, ...), detail.
  • Rock crystal Aztec crane analyzed in-situ by Raman microscopy in the Musée de l'Homme, Paris. (Ph. D.C. Smith)
  • Aztec ceremonial sculpture, department America of the Musée de l'Homme, Paris. (Ph. D.C. Smith)
  • Analyses of pre-Columbian rock and crystal objects (Teotihuacán mask), <em>in-situ</em> in the Musée de l'Homme, Paris. (Ph. D.C. Smith)
  • Analyses of pre-Columbian rock and crystal objects (ceremonial sculpture), <em>in-situ</em> in the Musée de l'Homme, Paris. (Ph. D.C. Smith)
  • In-situ Raman microscopy analyses of a 17<sup>th</sup> c. Florentine table (Muséum National d'Histoire Naturelle -MNHN). (Ph. D.C. Smith)
  • Xray diffraction (GADDS) analyses of alteration products crystals.




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