Sunday, September 30, 2012

Determining the Authenticity of Jade (Part 3)

Upper left, under magnification the resin backing demonstrates
round gas bubbles. Bottom right, This jadeite cabochon is hollowed
out to enhance the color. For protection, it has been injected with resin
and then bezel set with a closed backing to conceal the tampering.
Photo Copyright: Richard W. Hughes
Photo credit: Palagem
by Angela Magnotti Andrews


Once you’ve chosen a piece for purchase, be sure to inspect it closely. Look for inconsistencies in tone and color. Though jade is naturally variable in color, even sometimes in the same piece, you should be able to detect natural variations versus stains from dye. You may want to bring along a magnifying glass so that you can look closely at the texture and color distribution.

True jade should be grainy and/or dimpled in appearance, even when highly polished. If the piece you’re holding is too smooth or too glossy, you may be holding a fake or an overtreated piece of low-quality jade. Though new polishing techniques have diminished the dimpling (“orange peel effect”), jade will still appear matted or grainy rather than glass-smooth.

When looking at a piece of mounted jade jewelry, you’ll want to pay very careful attention. If possible, request that the stone be removed from its mount so you can inspect the back. A common tactic for passing off cheap substitutes is to paste a thin layer of true jade over the top of a piece of colorless plastic or green resin. They will feel bold in claiming it is true jade, since it does have some true jade in it. You will be able to see the layered effect by looking at the piece without its backing.

For an even closer inspection, you will need a loupe or microscope and table lamp. These are worth investing in if you’re serious about collecting or buying gemstones for therapeutic use. For jade’s multi-crystalline structure, you will want to use reflected light to inspect for inclusions. Under higher magnification, you should be able to see very clearly jade’s fibrous structure and its natural inclusions.

Read Part 4.

BIBLIOGRAPHY
1. "Case Study: Jade and its Historic and Modern Meanings for Trade." The Trade and Environment Database. Accessed September 19, 2012. http://www1.american.edu/ted/jade.htm.
2. Dietrich, R.V. "Jade (jadeite)." Stoneplus. Last updated April 16, 2012. http://stoneplus.cst.cmich.edu/Default.htm.
3. Dietrich, R.V. "Jade (nephrite)." Stoneplus. Last updated January 20, 2012. http://stoneplus.cst.cmich.edu/nephrite.htm.
4. "Jade." International Colored Gemstone Association. Accessed September 26, 2012. http://www.gemstone.org/index.php?option=com_content&view=article&id=121:sapphire&catid=1:gem-by-gem&Itemid=14.
5. "Jade Gemstone." Sunny Ray website. Accessed September 26, 2012. http://www.sunnyray.org/Jade-gemstone.htm.
6. Keverne, Roger, editor. Jade. New York: Lorenz Books, 1995.
7. Leaming, Stan and Hudson, Rick. Jade Fever: Hunting the Stone of Heaven. Heritage House Publishing Co. Ltd.: Surrey, BC, 2005.
8. "Nephrite." Optical Mineralogy. Last updated May 15, 2009. http://opticalmineralogy.com/the-silicates-mineral-class/nephrite/.
9. "Power of Stones, The: Jade." Angelfire. Accessed September 26, 2012. http://www.angelfire.com/de/poetry/Gemstones/jade.html.
10. Sun, Tay Thye. "The Changing Face of Jade." SSEF Alumni Newsletter, No. 3, January 2006.

*Clip art courtesy of The Graphics Fairy

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