Clarity Enhancement occurs when a gemstone has a foreign substance (like oil) inside of it to mask some of its inclusions. Typically, gemstones can have some nominal levels of oil residue that linger after the cutting process. There is a big difference between trace amounts and deliberate amounts of fillers. Planned treatments can come from substances like glass and polymer resins. Planned treatments can also become acceptable in the trade. Emeralds are an example of a stone that is usually treated with oil to improve its appearance. All treatments, including ones used for clarity enhancement must be disclosed. When buying any gemstones, the seller has an ethical obligation to disclosure any treatment of any kind. Every buyer should be cautious when considering an Alexandrite, which is why we highly recommend always getting a lab report to help identify if the alexandrite has clarity enhancement treatment.
Labs look for clarity enhancements or treatments as a standard. The more reputable lab, the more careful and reliable the reports will be in identifying treatments. In our experience, labs will examine these levels. Treated Alexandrites are worthless. That is why all our alexandrites are natural. Despite the negatives of treatments, sometimes the filler residue in Alexandrites is left by accident. In these circumstances, these traces are so low and insignificant that labs may consider them so inconsequential to even mention in the report. However, if the enhancement or residue is significant, they will make a note of it on the report. Clarity Enhancement in Alexandrite can either occur by accident, or because someone may try to hide inclusions.
The process of removing the residue used for clarity enhancement is easy. This method is not 100% proven, but we have successfully used it.
You will need:
Fill the container with enough alcohol to cover the entire stone. Let the Alexandrite Stone soak in the alcohol for a minimum of 24 hours. Re-submit the alexandrite report for an update. Generally, we recommend doing this process before submitting Alexandrites to labs.
Generally, we recommend doing this process before submitting Alexandrites to labs. This way you reduce your risk of getting a stone that is clarity enhanced. Alexandrites that do not have any treatment are always more valuable.
For example, GIA made a note about Clarity Enhancement on this 0.27 round Alexandrite. See GIA Report above under “Treatment.”
On GIA’s website, if you look up this report, there is a brief summary explaining what the clarity enhancement is:
Almost any gem with fractures can have its clarity enhanced. The process involves filling fractures that reach a gem’s surface using a variety of fillers, including plastic, glass, polymer resins, and oil. The filler must have a refractive index (RI) that is close to that of the gem. This makes the light pass through it in much the same way as it passes through the surrounding gem, making the material and the fracture it fills much less visible. Many different oils can be used for this process but the most common is cedar wood oil. Sometimes the stone just soaks in the filler, but the filler is often gently heated so it becomes more fluid. It’s also common to remove air from the fractures by subjecting the stone to a vacuum. Most of the fillers in this category are colorless because even a slight tint can negatively affect a gem’s color. Although emerald is the most commonly fracture-filled gem almost any transparent colored gem can be treated in this way including beryl, chrysoberyl, diopside, garnet, spinel, tourmaline, and zoisite.
Alexandrites with Clarity Enhancement are not common. Nevertheless, at The Rare Gem LLC we do not carry any Alexandrites that have been treated. Furthermore, we do not carry any lab created or man made synthetic Alexandrites. These imitation Alexandrites are not considered rare. They have no resell value, and should be avoided. Rarity consists of many factors. Not having treatment is a main component.