Let's go traveling thru the Southwestern United States, visiting Arizona where we have many locations to find Blue Turquoise, in Nevada we will visit the Comstock Load and get Silver and then head to Colorado where in the Thunderegg Mine we will acquire Black Agate. Throughout the centuries, the peoples of the Southwest gathered, traveled and exchanged their goods. Out of the mix comes the Southwestern Style of Jewelry.
Turquoise comes in many colors, shades and types in today's market. To help understand a bit, the following is provided----
Natural - This comes directly from the mine. It is cut shaped and polished and set into jewelry. It has no man made treatment or additives other than a polishing compound that adds to its luster. Several pieces of natural Turquoise from Arizona, can be seen to the right and are beautiful with very little polishing. Most stones in this state are very close to gem quality. The coloration of natural Turquoise can darken as oils from the skin work its way into the stone over the years, especially of not properly cleaned.
Stabilized – This is a natural turquoise usually in nugget form, but does not hold a luster. It is submerged into a stabilizing compound and dried, cut and prepared for jewelry. The turquoise has not been altered. The pores of the stone have been filled with a clear resin that makes the stone usable. This process allows for diversity of shapes and possibilities in jewelry making. Color Stabilized stones are considered altered and sometimes color has been added in this process. This in not necessarily bad, but it has less value than a piece that is naturally colored. Stabilized Turquoise usually does not change color with wear and because of its hardness, wears better in jewelry.
Treated - This form of color enhancement has been used for thousands of years. It is done as discussed earlier by submerging Turquoise stones into animal fat or vegetable oil and later air dried. Normally the color will not last very long. A new variety on the market, called "Motaska" and "Majave" Stone is much more stable and retains its color as well as being infused with gold, silver and copper.
Fake and Synthetic – Ceramics, bone, celluloid and plastic are used to imitate turquoise. Synthetic turquoise has a very natural matrix that is produced by placing stones in the synthetic “batter”.
Imatations - Then there are the imatations, in many cases natural gemstones that are beautiful in their own right, but due to the fact they accept dyes, many times are dyed the various turquoise colors and then are sold by unscrupulous dealers as real Turquoise. Price becomes the real determining factor when it comes to seperating real Turquoise from dyed Howlite, Magnesite or Ivoryite.
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). A picture of a true Black Onyx specimum is seen below. True 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.