I recently completed my first GIA (Gemological Institute of America) course online. I learned SO much! If you are in the market to learn about gemstones for your own jewelry making, or to become a more educated buyer, GIA’s Colored Gemstone Essentials course is extremely informative. One section goes over the common treatments of stones and how to care for them since they have different cleaning and maintenance requirements than untreated stones. I thought I would start out by focusing on pearls since they are very common among women of all ages. I usually wear my pearls all day, everyday. I sleep in them, shower in them, and I even recently played a kickball game in the 80-90 degree heat of Texas while wearing them. Shame on me! After reading this post, you’ll understand why that was such a bad idea!
– a chemical used to alter / reduce a component of, or the entire color, of a porous gem. Some gemstones are bleached and then dyed, a form of “combination treatment.”
1. The most commonly encountered bleached gems include:
Jadeite jade – Jadeite is often bleached with acid to remove an unwanted brown component from the material. Bleaching in jade is typically part of a two-step process: because acid bleaching causes the material to become slightly porous or susceptible to breakage along fractures, it is then subsequently treated with polymer impregnation to fill these open spaces to produce a better overall appearance.
Pearls – All types of pearls are routinely bleached with hydrogen peroxide to lighten and improve their uniformity of color.
Other materials – Some coral, chalcedony and tiger’s eye quartz may be bleached to lighten their color.
2. Detectability – Bleaching as a one-step process is virtually impossible to detect in most cases. The second step, impregnation with polymer compounds, is easier to detect by a qualified gemological laboratory using magnification and more advanced analytical techniques.
3. Encountered in the trade – Frequently in pearls and jadeite.
4. Durability factors – Acid bleaching causes a breakdown in the structure of most materials, so as a stand-alone treatment, leaves materials vulnerable to breakage. Most bleaching is followed by impregnation to improve durability and strengthen perceived color
5. Special care requirements – Bleached gems tend to be more brittle, and they may be much more porous and thereby more absorbent of human oils and other liquids. It is suggested that pearls be kept in a soft, dry environment to avoid surface damage.