Now that we have covered some of the elements of gemstones, let’s look at some specific stones.
Turquoise is one of the most popular stones used in jewelry and can be found in both traditional and modern designs. In my last write-up I mentioned the fact that turquoise is almost always treated by stabilization before it is used in jewelry. I would like to follow up on that to explain it a little more, and also discuss some alternatives for turquoise.
Turquoise is an opaque stone with colors ranging from light blue to blue-green, and may or may not have darker colored veining through it. It is a copper aluminum phosphate (an organic compound) with the copper causing the blue coloring and the aluminum causing the green coloring. The bluer the stone is, the more valuable it is. According to the American Gem Trade Association (AGTA), “Turquoise is among the oldest known gemstones- it has been mined since 3,200 BC.” Because of its popularity, turquoise is getting harder to find, especially high quality turquoise. Many mines have already closed because they were depleted and this is causing an increased production of lower quality turquoise, which needs more stabilization to work in jewelry.
In regards to its treatment, turquoise is often treated either with resin, epoxy, paraffin wax, or plastics. These chemicals absorb into the turquoise, which is naturally porous, and strengthen it while also improving its texture. Untreated turquoise can be used in jewelry, and when it is, the value of it is much higher than treated turquoise. Stones which have more of a blue color contain more copper and are harder than stones which are have more of a green color. These stones usually are not treated or not treated as much.
Because of the increasing rarity of quality turquoise, many jewelers have started to use what is known as chalk turquoise as a substitute. According to Fire Mountain Gems and Beads:
“Chalk turquoise is a form of natural turquoise that has a white chalk-like consistency. It has the same chemical composition as turquoise, only without the copper (it’s the copper that causes the blue turquoise color). Chalk turquoise is also a bit softer than regular turquoise. It is dyed pleasing colors and stabilized with resin to produce beads that are hard enough to use in jewelry. Chalk turquoise is considered less valuable than regular turquoise because it does not contain the minerals that create the rich blue and green colors.”
I will admit I often use chalk turquoise in my jewelry designs for its color and affordability. I do not generally use it as a substitute for real turquoise. I use it as if it is its own stone just like any other colored stone.
Another form of creating the turquoise look is to use “reconstituted turquoise.” To create this, manufacturers grind up turquoise stones which are too small or low quality into a powder. They mix it with a binding agent, such as resin, and then it is dried and cut into pieces. This form of turquoise should always be noted as “reconstituted” and not sold as real turquoise.
Lastly, we have synthetic, or imitation, turquoise. This is generally made of a plastic, ceramic, resin, or other reconstituted stones which have been dyed. Synthetic turquoise is used primarily in your less expensive jewelry.
A natural alternative to turquoise is magnesite. According to Fire Mountain Gems and Beads, magnesite is a mineral with the same crystal structure as calcite, “a calcium carbonate with a hardness and texture similar to turquoise and marble.” It is generally white or close to white in color with darker colored veining throughout it. Because of this veining, magnesite is often dyed to look like turquoise.
Due to the increased demand and decreased availability of turquoise, it is getting harder to find quality turquoise in jewelry. Because of this, many jewelry manufacturers are going to alternative ways of creating the turquoise look, while keeping the cost affordable. If you find a piece of jewelry that is advertised as turquoise but just doesn’t look quite right, ask about it. Generally, if it is not real turquoise, it should be advertised as such, but it never hurts to ask.