Thursday, February 10, 2011

Some gemstone basics

I am going to be highlighting a different gemstone a week in my blog for the next several months, so I thought that before I make the first post, I would do kind of a breakdown on the basics of gemstones and some of the terms used. I know that not everybody who reads and follows my blog creates jewelry. To me, beauty is in the eye of the beholder, so what may appear to be a mediocre looking stone to one person, is absolutely beautiful to another. I think it's all about the color and the pattern in each stone. As with all things created by Mother Nature, no two will ever look alike.

Stones are measured on the Moh scale of hardness. This is a scale that was developed in 1812 by mineralogist, Frederich Moh. In researching this series, I have seen his nationality listed as German, French and Austrian. It compares the hardness of one substance against another. It is the most commonly used measure today. Later, the sclerometer was invented and it measures absolute hardness. In the majority of stone listings, though, you will see the hardness as the Moh scale. In this scale, talc is a 1, and a diamond a 10.  The hardness of a stone is an important consideration when designing or purchasing stones. 
You need to be aware that the beautiful piece of coral in that ring is a 3-4 on the Moh scale, and to take care not to bang your hand up against something that could scratch or nick it.

Some of the most common mineral families of stones are beryl, feldspar, and quartz. There are a variety of colors among these families. These variations are caused by the different minerals that happen to be in the stone. For instance, the blue in turquoise is from copper.

Stones are treated in many different ways to enhance or stabilize them. For example, most turquoise on the market today is stabilized to give it more durability and improve the appearance. This is most commonly done with a resin of some sort and is often done with stones that are considered to be somewhat porous. Often stones are heat treated. There are many different way of doing this. It is done to bring out the depth of color. Some stones are irradiated, then heated to further deepen the color. Irradiation of gemstones in the US, is governed by the Nuclear Regulatory Agency to be sure the stones contain no residual radiation. A lot of gemstones are dyed to bring out or change the color, or to enhance the veining. Dyeing is usually followed by some sort of heat treatment to bond the dye with the stone so it won't wear off on the person wearing it. Black onyx is a prime example of dyeing because it does not exist in nature. More on that in another post. There's nothing wrong at all with stones that have been treated. Most sellers of stones or finished jewelry will state in their description that the stone is treated and how. Sometimes they don't know if a stone has been treated, so it's best to proceed on the assumption that it has, in some way, been enhanced.

There is a lot of glass being passed off as gemstones today. Among the most common of these are “opalite”. It's an opal looking glass. Fruity quartzes are another glass stone being passed off as a gemstone. Among these are blueberry and strawberry quartz. They all make lovely jewelry, but they aren't gemstones. If you see a stone or piece of finished jewelry you like, but aren't sure about the 
stone, google it to be sure. The vast majority of handcrafted jewelry makers, including myself, want you to be knowledgeable about your purchase and we want to be knowledgeable about what we sell.

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