Treatments to Enhance Gemstone Quality
From ancient times, precious stones that lacked the best characteristics found in gemstones of the highest quality have been subjected to enhancement procedures to make them better. The first person to do so was Pliny the Elder, who did so in his Historia Naturalis.
Today it should be compulsory to report which are the treatments the gemstones have undergone.
The international body that regulates the trade in fine gemstones emphasizes the necessity of complete transparency in the purchasing and selling of gemstones as well as in the disclosure of how many and what kind of treatments each gemstone has received.
Contrary to what many traders believe, this does not take place because doing so may mislead and confuse customers about a situation that is actually rather regular.
They would be right, but that is not the case because the assessments of treated and untreated gemstones vary. Instead of buying anything purely because it's attractive to the eye, it's critical to consider the price because it might vary significantly. By doing so, you can make a wise investment.
Treated gemmiferous materials should be described in a gemological certificate following this technical classification:
Heated: materials that underwent a thermal treatment.
Oiled: materials whose fractures have been filled with oils or other oily colorless liquids.
Oiled with pigments: materials whose fractures have been filled with colored oils or other oily liquids.
Diffusion treated: materials that underwent a thermal-diffusion process with addiction of chromophore chemical elements.
Impregnation treated: materials whose pores have been filled with colorless substances.
Irradiated: materials whose color was modified through invisible radiation or bombarded with atomic or sub-atomic particles.
Filled: materials whose cavities have been filled with fluid colorless or colored substances that harden after application.
Coated: materials that have been totally or partially coated with other substances.
Dyed: materials whose pores, cavities and fractures have been filled with colored substances.
Heating is one of the most used treatments for colored gemstones. This procedure involves heating gemstones to high temperatures (up to 3000 degrees); this causes electrons to flow around inside the crystal, which enhances color.
This procedure is quite typical for sapphires; in this instance, it does not lower the price but is a benefit for completely natural sapphires, which are getting harder and harder to find.
The oiling process is applied to almost all emeralds in order to conceal the tiny surface fractures that are extremely typical in these minerals. Because the original material is of such poor quality, further treatments lower the price of gemstones to 1/100 of their original worth.