What is Gemeology ? by Anu Manchanda

03/10/2019

What is gemology ? by Anu Manchanda

From the Gemology Institute of America (GIA), Anu Manchanda came presenting what gemology is. The GIA's aim is to promote knowledge about gems for companies, customers, graders, mines and sellers. Her short description of gemology would be that it is a blend of a few things: the study of gemstones as in applied crystallography, business as in industry and sales and markets, art for the jewellery aspect and finally a passion. She then described what it actually entails to be a gemologist.



Gemology is used by a range of professionals: retail sales professionals, appraisers, jewelry buyers, wholesalers, designers, manufacturers, trade journalists and research lagoratories for treatment of gemstones or synthetic manufacture. The production of synthetic gemstones is now very important in multiple field ranging from abraders in industry to scientific grade equipment.
At GIA, the gempstones are separated as diamonds and coloured gemstones groups as diamonds are regulated in a specific fashion. The GIA is involved with the trade market, gemstone identification, diamond and coloured gemstones grading, the basic optical and physical science relative to gemology and finally the sales techniques. She then discribed the steps they go through when they are handed in a gemstone.
First it is needed to identify the gemstone. The best tool for this first is tho use the naked eye where wth the right expertise ~50% of the work is aleady done. This is a prime quality for field and exploration gemologists. Then the similar gemstones are differentiated relative to their Refractive Index (RI) which is distinct per crystal. Then they are analysed through the microscope. These techniques permit to make the difference betweens look-alikes and synthetics, very important especially in the diamond trade.

The gemstones, if send for lucrative purposes, can be treated to overcome their shortcomming. Breaks or cracks can be filled by material with the same RI than the crystal of laser drilling can be used to remove impurities.
An important aspect as well is the grading of these gemstones, for coloured gemstones their colour, aside from their purity is a defining factor. Colour of the coloured gemstones are given a rank qua tone, hue and saturation which grately influence their final grade. The colours of cloured gemstones are directly linked to theire relative concentrations in impurities making certain tints very rare and thus very valuable.
For diamonds being transparant, other criteria are used for grading, notably the four C’s: colour, clarity, cut and carat. Depending on their Nitrogen content diamonds quand be slightly tinted. A slight tint would usually bring the value down of the product whereas a transparant of very deep clour will bring the price up. Clarity measures the proportion, shape and relief of the inclusions, focusing of the optic aspect. The cut is the man influence parameter and carat finally is relative to the size of the gem. The mine of origin can also have an impact on the price of the gem.
The exploitations of gemstones bring along multiple questions: the adventages and disadventages of industrial gems, the ethics in the mining, the environmental impact and the steps taken or yet to be taken to tackle those problem. Questions to which she failed to answer.