Nevertheless, we must say, that until the first studies were preformed by Dr. Photo: Len Rummel, 2004 Click to View Full Size But How is common heat treatment performed?Although there are many variations of the procedure and a number of gems are involved, we can summarize by saying that there are two main elements involved: the temperature and the environment (atmosphere composition and pressure) in which it took place.An reducing or oxidizing environment (higher or lower oxygen percentage) will allow, as an example, the exsolution of the rutile needles band of silk with consequent improving of the transparency in milky, whitish or cloudy stones.The procedure could enhance, reduce or eliminate the asterism phenomena visibility.Sapphire engagement rings have been used for weddings since the 1880's and have recently been gaining in popularity.Blue sapphire is the traditional birthstone of September and is very durable, making a sapphire ring suitable for every day wear.
This will be apparent when you have a look at some elementary ovens that are still operational nowadays in the Chanthaburi area, Thailand and Cambodia (photo 1).
Nowadays heat treatment is widely accepted (if disclosed, of course) and in some cases (tanzanite, tourmaline, zircon, quartz etc..) is considered a so consolidate routine that very often the disclosure is unmentioned (among professional) in business procedures.
It’s good to know that in those described stones, only rarely the treatment will be considered of discriminative importance from the price point of view, in many other situations (in sapphires and rubies, for example) the importance of this factor is absolutely unavoidable.
The "healing of fractures is very important to distinguish from other heat enhancements methods, as it is more penalized when noted in Gemstone Identification Reports issued by major labs, because foreign elements are often added.
Truth be told, as we shall see ahead, even with simple heat treatments there are chemical exchanges between the gem and the surrounding atmosphere, but most labs consider this of minor significance..