Post by account_disabled on Mar 6, 2024 3:53:37 GMT -5
Almudena Gómez . Chief Gemologist at the IGE Analysis and Certification Laboratory Gem treatments Treatments are carried out on gems with the aim of improving some of their quality parameters , such as color and, in some cases, purity. By improving the quality parameters, the gem can increase its value in the market. Some treatments are serious and others are not, but all are allowed in commerce, as long as the buyer is duly informed. According to the International Jewelry Confederation (CIBJO) , general information should be given in the case of frequent and stable treatments, while, if the treatment is severe and unstable, specific information should be given, as it can affect the gem negatively. . Heat treatment Heat treatment has been carried out for thousands of years; It is difficult to specify when it emerged, but already in 2000 BC. C. The first gems heated to improve their color date back to India and Egypt.
The process is quite simple and little has changed compared to the one that was used at that time. It consists of placing the stone in an oven at high temperatures, with the main objective of improving or modifying its color. It is currently one of the most frequent treatments applied to gems and, as it is very stable, specific information to the buyer is not necessary. If a gem has undergone this Cell Phone Number List treatment, its market value will not decrease, but if a gem has not undergone heat or any other type of treatment, then its value may increase significantly (up to 50%). In the particular case of corundums, heat treatment is used to improve the color and/or purity, to increase its quality grades (photo 1). It is mainly applied to less saturated sapphires to intensify their color, or to eliminate silks and thus increase their transparency; in rubies to eliminate the purple tone and thus highlight its reddish nuance, in addition to being able to eliminate silks as well.
The treatment in turn can cause, when the temperature drops again, the rutile to recrystallize again and rutile silks to form again, thus generating a marked asterism. Sapphires subjected to heat treatment Photo 1: Sapphires before and after having been subjected to heat treatment. Author: AIGS The increase in temperature begins to be perceptible in the gems from 1300ºC, but at lower temperatures no evidence usually appears, so it is difficult to determine a heat treatment at less than 1300ºC. Identification of heat treatment in corundums To determine whether a corundum is heated or not, it is very important that we observe the inclusions they present, since this is what will help us determine whether or not the gem has undergone said treatment. The ideal way to observe the inclusions is a microscope (photo 2), but in many cases a 10x magnifying glass (10X) may be enough to observe evidence of temperature increase.
