Gems & Gemology, Summer 2017, Vol. 53, No. 2

Oiled Ruby: A Remarkable Visual

E. Billie Hughes
Oil in ruby contrasts with gem’s bodycolor.
The red color of the oil within the cavity of a ruby displays a remarkable contrast with the bodycolor of the gem. Unlike the flattened bubbles regularly encountered, a rounded bubble attests to the size of the cavity containing the oil. Photo micrograph by E. Billie Hughes; field of view approximately 2.5 mm.

As laboratory gemologists working in Bangkok, we often encounter gems that have been treated with oil to minimize the appearance of fissures. Most of these  stones come from Myanmar, where many vendors consider oiling an accepted standard procedure to enhance their goods, particularly ruby and spinel (http://www.lotusgemology.com/index.
php/library/articles/315-lotus- gemology-lab-alertfor-oiled-gems). Furthermore, red oil is commonly used not only to improve clarity, but also to enhance the color of the stone (in Chanthaburi, Thailand, it is sold under the brand name “King Ruby Red Oil”). Often this treatment can be identified by flattened gas bubbles in the fissures or by droplets of oil seeping out of the fissures on the surface when the stone is gently warmed by microscope light or hot point.

The image above shows a small surface-reaching cavity filled with oil in an unheated 1.75 ct ruby from Myanmar. Unlike other examples we have seen, this remarkable gem contained enough of the filler to easily photograph the striking red color of the oil itself within the cavity. With oblique fiber-optic lighting, a stunning image of this enhancement in situ was made possible, turning even an otherwise commonplace forensic determination into an aesthetic exploration of the micro-world.

Learn More About Ruby

Why We Love Ruby
Explore ruby history, research, quality factors, and more in the GIA Gem Encyclopedia.
Read More

2017 G&G Challenge

Test your knowledge of our 2016 content by taking our annual Challenge.

The last day for submissions is
Friday, August 11, 2017.
Take the G&G Challenge

Richard T. Liddicoat Gemological Library

Search GIA's library catalog of 57,000 books, 1,800 videos, 700 periodicals, and the renowned Cartier Rare Book Repository and Archive.
Visit the GIA Library

You Might Also Like

Find a Retailer
learn more
Shop the Campus Store
Learn More
Quality Assurance Benchmarks
Learn More
Gems & Gemology
G&G Fall 2017 Edition
Learn more