Thermal Shock and Gemstones

We received a desperate email from a person out there who had purchased a Tanzanite that didn't seem to have any issues initially, but after being set it was Ultrasonic Cleaned and then Steam Cleaned. Both are pretty typical when work has been done on a setting, but one needs to be careful and know which gemstones to be cautious about - though many or most have no issues at times. Read the original email and general thoughts below:

Please help!

We purchased a 6.7 ct Emerald cut Tanzanite while in the Caribbean. Upon returning home to Toronto, we took the stone for an appraisal. He appraised it in the following way: Clarity VS Type 1; Colour med. Dark v. sl. grayish v Blue; Cut: Medium; Value $5,190.00 C$. There were no visible inclusions.

We then had the stone set in an 18 ct white gold ring surrounded by diamonds. After setting the stone in the ring they polished the ring and then placed it in an ultrasonic cleaner and then rinsed it under water. An inclusion occurred through this process that runs the length of the stone (top to bottom) in the center that is very visible. The jeweller says he is not responsible and says it is because the stone was flawed and it was heat treated to cover the imperfection (filled with oil) and that the ultrasonic cleaner made the inclusion visible. The people we bought it from say that Tanzanite is heat treated to create the blue color and the stone by its very nature has liquid filled inclusions and if it goes through a rapid heating or cooling process (thermal shock) these tiny inclusions can crack the stone or create larger inclusions. What do I believe, the jeweller is taking no responsibility and the stone merchant equally does not believe they have any responsibility to “right” the situation.

Response:

You can also email GIA (gia.edu) and get their thoughts. Emeralds are typically oiled, not Tanzanite. Tanzanite, like Emeralds and others, could be damaged due to an ultrasonic or steam cleaning and it is best to avoid both processes. This is pretty much known info and available information. You can probably find out more by using search engines - "Tanzanite, Ultrasonic", "Tanzanite, Steam Cleaning", "Durability of Tanzanite", etc. Some stores will not even set Tanzanite as they feel it is a potential risk - however, any good goldsmith works around issues with Tanzanite, Emerald, Opal and ALL other gemstones. An inclusion of what you describe, whether filled or not, should have been picked up during the appraisal process if it existed - assuming knowledge of the appraiser. Again, we have never heard of Tanzanite being filled with anything - there is NO need.