Gemstone Trivia

There are several scales that are used by Gemologists to determine hardness, durability or the scratch resistance of gemstones. The one that is most widely recognized is the Moh scale, which is really a table that indicates the scratch resistance of gemstones. A German minerologist by the name of Friedrich Moh developed a scale in 1822 to compare the scratch resistance of gemstones. It has become universally known as Moh's scale, with Diamond being a 10 or the most scratch resistant to Talc at a 1, which is the least scratch resistant.

I bring this up because most gemstones are enhanced in one way or another to increase durability, reduce scratch resistance or improve the look of the stone, or to even create a new look. For example, Carnelian can be heat-treated to produce that dark, rich reddish-orange color as found in some of the beads pictured below.

Generally, high scratch resistance is desirable for gemstones, and a Moh's hardness of 7 or higher is important. The principal reason is that a common cause of abrasion is sand, which is silica grit (quartz), and is commonly present in dust. Stones which are softer than quartz are not suitable for everyday use as facetted jewelry gemstones, particularly in rings. Some gems, such as Pearls, Coral, Turquoise, Lapis Lazuli, Amber, and Opal are quite soft, but are usually polished into cabochons or beads, rather than facetted, and therefore do not show scratches so easily. All these gemstones have been successfully used in jewelry for many centuries.

Most gemstones used in jewelry have been treated to improve their appearance. Treated gemstones can be a good choice when you know what you are buying and pay a price that reflects a stone's true quality. There are Industry Standards that indicate the type of enhancement and whether they are permanent or not. You’ll probably come across the phrase “enhanced as per Industry Standards”. So don’t be worried if the gemstones in your piece of jewelry have been enhanced. Sometimes enhancement can make a gemstone more valuable. Two of the gemstones that I would like to discuss that are usually enhanced are Turquoise (a mineral gemstone) and Coral (an organic gemstone) which are consistently at the top of the list for the most popular gemstones and they are always in fashion. Another term that you will hear is Stabilization, or that a stone has been stabilized and it is usually used with stones that are less than a 7 of the Moh’s scale. This is especially true with Turquoise and Coral.