In 1980 when I graduated as a gemologist from the Gemological Institute of America in Santa Monica California, it was relatively easy to detect, analyze and identify the different treatments that existed to beautify gemstones; All you needed was a basic gemology kit that could include a good microscope, refractometer, polariscope, and an ultraviolet lamp; It was not even necessary to declare the changes or treatments, simply in the reports of precious stones, the result of their analysis was given, placing their species and their variety, since the trade did not require more details.

On the other hand, now in the second decade of the 21st century, not only a lot of knowledge and experience are needed, but in some cases, high-tech equipment to be able to detect the various ways that exist to beautify gemstones. In addition, it is very important to declare the truth about the changes or types of beautification that have been made to the precious stones, so as not to fall into legal problems. This has led gemstone dealers, jewelers and even end consumers to rely on gemology laboratories demanding gem reporting to market gemstones.

In this article we will show the main gems that can have some type of treatment and the procedure to analyze them.

Types of beautification

There are two types of embellishment, one that serves to improve or change the color of gems, which is the case of treatments for rubies, sapphires, diamonds, Tanzanite, quartz and topaz; and the other that is used to improve clarity by filling the cracks, commonly used for emeralds, rubies and diamonds.

RUBY AND SAPPHIRES
Thermal beautification

The vast majority of rubies and sapphires are heated to enhance, change, or remove their color; improve its transparency by melting rutile inclusions or to cure fissures with molten residues. This has meant that in the case of a ruby ​​without treatment, due to its rarity, it can cost a fortune.
The procedure leaves amorphous substances in the fissures, causing many problems among traders, as it causes the stone to have small unnatural parts. For this reason, an agreement was reached between the merchants and the gemology laboratories that allows the amount of residues in corundum to be classified into five levels: None, minor, moderate, significant and very significant. This allows the ruby ​​to be valued depending on the amount of residue.

The best way to detect this treatment is by using the microscope, since when the stone is exposed to high temperatures, the included crystals melt, losing their original shape and in some cases leaving a halo around them. It is also very common to observe traces of what were rutile needles, as well as its treatment when amorphous residues are found in the cracks.

Diffusion treatment

The diffusion of titanium on the surface of corundum (ruby and sapphire) was one of the best known treatments in the 80s. This produces blue, red, and yellow-orange colors with some pink. Fortunately, it is very easy to detect since when placing the stone immersed in methylene iodide, colored areas can be easily seen at the junction of the facets using diffuse light. This type of corundum has little value, since just polishing the stone can lose its color.

On the other hand, the diffusion of beryllium gives a pinkish orange color, which is one of the most difficult treatments for gemologists to identify. “Padparacha” Hindu word as this stone is called, it is one of the most appreciated and expensive. At the beginning of 2000 many of these stones appeared that at first it was believed, were treated by heat, until it was possible to demonstrate that it was a new method by diffusion of beryllium, which depending on the treatment time, can penetrate all the stone, making it impossible in some cases to be identified. If the treatment has been partial, it can be detected under a microscope (when placed in immersion), where a pink heart is observed, surrounded by an orange ring.

By combining beryllium iron treatment, light yellow, light blue and colorless sapphire can be transformed into deep yellow; the pink one changes to the characteristic color of the “padparacha” or in orange, and the dark brown red, in bright red. The only equipment capable of detecting this treatment when it has penetrated the entire stone and cannot be observed with a microscope is plasma masses with laser ablation, one of the most expensive, which means that very few laboratories have this service.

Irradiation

This method has been used to yellow corundum, but it is very unstable and with only ex