Scientists at the Institute of Minerals and Materials Technology (IMMT) found a new way to improve color, clarity and luster of red ruby — microwaves. Rubies are one of the world's most popular gemstones and this study could provide many owners a means to improve the look of their beloved stones.
Published in Spinger's journal Applied Physics A, the study has shown that even if heat treatments were used in the past, this is the first time that scientists used microwave heating as a method to improve ruby's color.
"Microwave heating, an unconventional method of fast thermal excitation, produces new results in gemstone like ruby," said Shubhashree Swain, author of the study.
"The study provides a new vista for future workers in the area," he added.
Usually, scientists use heat treatments to improve the color saturation, trading value and clarity of gemstones. As the technology improved, they applied chemicals or surface coatings, used beam irradiation and other sophisticated methods.
This study proposes a new and cheaper means to improve the overall look of red ruby through the use of microwaves. This method has been proven useful in other materials as well; like metals, composites and ceramics.
To test the new method, they collected rubies from Sinapali, Odisha in India and treated them in a microwave for a few minutes at 1,500-degree Celsius. To compare treated rubies in the microwave with those which were not treated, they used different techniques including X-ray diffraction, fluorescence spectrophotometry, X-ray photoelectron spectroscopy, ultraviolet-visible spectroscopy and Raman spectroscopy.
The researchers have found that the microwave method made improvements in the gemstone's color and structure. The reddish black color of the stone turned to light pink, which believed to be brought about by changes in the stone's chromium, titanium and iron elements.
The microwave method has many benefits especially for the gemstone industry. It is an easier and less expensive way to treat gemstones than traditional heating. Aside from that, it provides uniform heating, it's an energy-saving method, and it's eco-friendly.
"The overall results demonstrate for the first time the effect of fast heating like MW on the microstructural properties of the gemstone and various oxidation states of impurity elements in the natural ruby," the researchers concluded in the study.