This content was first published on IGR – Italian Gemological Review no. 2 in 2017. The information provided here is therefore current as of the original publication date.
Identifying your friends the inclusions in an almost “biblical” way is an operation required and essential to tell the natural from the synthetic, like in a multi-episode thriller. Where will our investigation begin? I will try to apply the simple rule I have always followed over my thirty years of gemmological divulgation, that is to supply incredibly simplified concepts in order not to bore. Shall we try? Here we are. Simply ask yourselves:
- What kind of shape, colour and transparency does the inclusion that I am observing have?
- Can we refer such features to some specific mineral or not?
- Is the inclusion that I am examining associated to others having the same appearance or a different one?
- Can I repeat the surveys and the conclusions specified in the above items 1 and 2 for these latter?
- As a whole, do the inclusions present in the gem distinguish as for association, position, orientation, global appearance? If so, what type?
- Do the shape, colour, transparency, position, orientation, association with other inclusions having the same or different features, as well the global appearance as a whole, refer to a natural genetic environment or not?
- What types of genetic environment can we have and how this impact on the shape, the colour, etc., etc. of our inclusion/s?
Let’s start from this last question. First, though, I would like to still a more than presumed bias, that is: if I can not rely on a thorough training in mineralogy and geology, how the blazes would I ever be able to become familiar with all those abstruse names and concepts that appear before me? No fear. Have you ever been invited to a party where most of the guests did not belong to your usual circle of acquaintances and where you shook plenty of hands repeating your name to utter strangers who told you theirs?
At the end of the party, after all the alcoholic beverages, how many names and surnames did you manage to match to a face? If you answer “all”, you are either inveterate tombeurs de femmes or passionate and insatiable man-eaters. Well, if you do not belong to these last categories, you should be informed that the same will happen with inclusions. Only after the second, third or fourth meeting, names and surnames will be impressed in your memory, well associated to specific faces. The faces, in this case, are the traits of your inclusions (see above), the surnames will be the mineralogical species, while the names refer to the variety of such species. You will mostly just need to remember the surname. Examples: corundum (surname) in corundum (surname); pyrite (surname) in quartz (surname) or corundum; apatite in spinel; peridot in spinel. However, we could have spinel (surname) in ruby [variety (name), of the corundum species (surname)] of Burmese origin, or actinolite in emerald (a variety of the beryl species).
If, then, I whispered in your ear that, for the purposes of recognition, it’s not the identity of the inclusion to be determining, though its age when compared to the hosting crystal, an age that can be inferred by the external appearance of the inclusion and by the type of position and disposition in the hosting crystal, you should quieten down. This (duly) said, let’s go back to the genetic environment. This is strictly connected to the (natural or artificial) process that originated the forming of substances (natural, synthetic or artificial) and then also of the inclusions contained in such substances. But here we must leave you with bathed breath: you will discover the rest in the next episodes.
By Luigi Costantini*, published on Rivista Italiana di Gemmologia #2, September 2017.
* Prof. Luigi Costantini estabilished IGI International Gemological Institute School of Gemology in Italy in 1998. He is currently honorary president of IGI International Gemological Institute Italy.
