GEMSTONE JEWELRY - An Old Favorite, Turquoise !

Turquoise use in jewelry goes back to the early Egyptain times and maybe earlier than that. The Native American's use of Turquoise in their jewelry, especially from the southwestern United States, where it is plentiful, is still a favority among men and women alike.

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This design incorporates southwestern stablizied Turquoise tear-drop shapped pendant hung on silver from a necklace of Turquoise oval and Ivority barrel beads with Black Agate (Onyx) chips, silver plated highlights and a silver hook and loop clasp. Silver leverback earrings with matching Turquoise ovals complete the set.

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Turquoise is an opaque, blue-to-green mineral that is a hydrous phosphate of copper and aluminium. It is rare and valuable in its finer grades and has been prized as a gemstone and ornamental stone for thousands of years owing to its unique hue. In recent times Turquoise, like most other opaque gems, has been devalued by the introduction of treatments, imitations, and synthetics onto the gemstone marketplace. The substance has been known by many names, but the word Turquoise was derived around the 16th century from the French language 'turquie', for a Central Asian material which was a very early imported through Turkey from Persia. Today, Persian and certain southwestern United States Turquoise, especially Sleeping Beauty, commend some of the highest prices paid for this gemstone.

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Black Agate (Onyx) which is truely a died black Agate, is more common and perhaps the most famous variety, but not as common as natural Onyx. Onyx is a crypyocrystalline form of Quartz. The colors of its bands range from white to almost every color (save some shades, such as purple or blue). Specimens of Onyx contain bands of colors of white, tan, and brown. As stated, the pure black form which most people know as Onyx, is not a naturally occuring variety. Black Agate or poorly colored Onyx is heated and dyed black to come up with the pure black form so well liked within the jewelry industry.

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Ivoryite is a unique variety of an extremely fine grained mineral called Magnesite. It is a naturally occuring mineral and not man-made. It is found in Arizona and quarried by hand. Ivoryite has the creamy color, smooth texture, and satin luster of natural Ivory. It is slightly harder however than natural ivory.

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BLACK ONYX - a manmade variety of Chalcedony (Agate) !

Every now and then, a real surprise comes along and makes one step back and wonder about many other things. One such rendering took place this past weekend at the Southwest Gems and Mineral Society Show. Was told by a knowledgable lapidarist when looking at a display I had, than there isn't such a thing as "Black Onyx" which was included in several of the necklace sets I had on display. So started checking around, and the Earth Science Department from Trinity University was present with a booth, so chatted with them for a bit, and yep, no such thing as natural "Black Onyx". To make things easier to understand, here are some definitions of "Black Onyx" off of several different sites on the Internet.

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"Black onyx" is neither truly onyx nor truly black, but it is actually dyed chalcedony. According to some experts, it is produced by boiling slabs of gray chalcedony in a sugar solution. The sugar permeates the stone's "pores" between the submicrocrystallites and darkens the appearance of the stone. This dye/treatment is stable and requires no special care.

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Black Onyx - unknown in nature, it is produced by warming chalcedony in a sugar solution for several days or weeks. The stone in then placed in warm sulphuric acid. The acid reacts with the sugar, precipitating the free carbon. The black color is permanent.

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Black Onyx - Mohs Hardness: 6.5-7 - Treatment: Dyed for color uniformity - Color: clear to browns (See also Chalcedony as no such thing as Black Onyx). Onyx and Sardonyx are similar to agate, but Onyx has straight rather than curved bands. These bands may be in shades of browns, reds, tans, yellow, greens and rarely blues and will always have white. Since ancient Egyptian times, onyx has been stained to improve or change its color to an all black gemstone. All totally black onyx has been produced by soaking black agate (chalcedony)or other Onyx, especially clear, in a sugar solution, then heating it in sulfuric acid to carbonize the sugar particles. Found worldwide. Onyx is formed by the deposition of silica in gas cavities in lava, which results in the distinctive bands.

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So from now on the proper term to use with the 'little or big black stones' used in jewelry, should be either black Agate or black Chalcedony with the added comment "enhnaced by chemical treatments and is called black Onyx". One learns something new every day if you listen good.

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