How Do You Identify Gemstones?

We get this question a LOT from folks who come in with a piece of jewelry from their jewelry box or something they’ve received from a relative… “Can you tell me what stone this is?” What seems like should be a simple answer is rarely that easy.  Let’s talk about why gem identification requires some detective work. 

The Art and Science of Identifying a Gemstone

Gem identification involves finding clues and eliminating possibilities. What kind of clues? The optical and physical properties of the gem. For each of these properties we measure or observe, the smaller the choices of possible gems get. We continue to gather more information until we have a set of properties that can only belong to one gemstone. Not only do we rely on our experience with gemstones, but we use state-of-the-art technology for analytical examination, including microscopic examination of the item, and performing tests, like light refraction, dichroic testing, and absorption spectrometry to determine the gemological identity. There are several additional tests to detect any treatments like coating, dyeing, clarity enhancement, fracture filling, heating, irradiation, or oiling. It takes time, expertise, and the right tools to accurately identify a gemstone and its characteristics. 

My Gem Is Dark Blue So It MUST Be a Sapphire

There are many different gemstones that can be used in jewelry. Some gemstones are commonly used in jewelry like diamonds, sapphires, and rubies. Other gemstones wax and wane because of their popularity or even their availability. For example, Tanzanite was only discovered and identified in 1967, which is young in gemstone terms, so it wasn’t used in jewelry until later in the 20th century.  But, Tanzanite was instantly popular and highly in-demand because of its beautiful color. Availability of material plays a role too since there may not be enough gem-quality pieces to create mass-produced jewelry. A rare species of garnet, Demantoid garnet, was discovered in Russia in the early 1900s and was used primarily in the Czar’s jewelry; once that small, original, single source was exhausted, Demantoid garnet was not widely available, and no new material was mined until a new source was discovered in the 1990s. It continues to be a very rare variation of garnet not mass produced in jewelry and is highly sought by collectors.  

On the other hand, sapphire which is the mineral corundum, comes in all colors of the rainbow and is commonly used in jewelry because of its lovely color and hardness. Depending on the trace element content, sapphire varieties might be blue, yellow, green, pink, orange, purple, white or black.  If corundum is red, it’s considered a Ruby.  So, you may be surprised to find what you thought was another gemstone may in fact be a sapphire. And the opposite happens as well… if a customer brings in a ring with a blue gemstone, we can’t assume it is a sapphire. It could or may likely be a Sapphire, but it could also be another blue gemstone like Iolite, Tourmaline, Zircon, Tanzanite, Spinel, Benetoite, Kyanite, Sodalite, or Labradorite, just to name a few. 

Did you assume that the photo above was a sapphire?  It's actually an Iolite!

But It's OLD... It Must Be Real

We hear this a LOT! But it often is not the case. Just because great-great-grandma’s ring has a transparent red faceted stone in it, the age alone doesn’t indicate that the gem is a genuine ruby. It could be a different gemstone, or even another material. Synthetic gemstones have been around for hundreds of years, and often older pieces feature synthetics.  The ring pictured on the left is a synthetic ruby in a vintage man's yellow gold ring. The lady's ring on the right also features a synthetic ruby.  It’s always worth checking to make sure you know about a piece of jewelry or its gemstone before you decide what you will do with it.  

Where Did My Gemstone Come From?

We get this question occasionally too: “Can you tell me where this stone comes from?” Sometimes there are scientific ways to determine the geographic origin of certain types of gemstones, based on testing. Geographic locale can be determined for gems like emerald, Paraíba-type tourmaline, Alexandrite, and many rubies. For some materials, especially blue sapphire and some rubies, it is more difficult. There is a close relationship between the geological environment where the gem was formed and the physical and chemical properties of the gemstone that can be measured using combinations of increasingly sophisticated instrumentation. This process is more complicated and origin determination relies on a combination of traditional gemological observations and advanced analytical instrumentation.  We often rely on the services of laboratories like GIA or AGS to help determine gemstone origin, or we purchase gems from our gemstone partners who can provide the path of a finished, faceted gemstone from its original, mined source.  Pictured above is our loose gemstone partner, award-winning gem designer, Roger Dery, recently at a mine in Africa. 

Look Out Sherlock Holmes!

There are more than 300 types of precious and semi-precious gemstones that are or have been used in jewelry.  Some are more wearable than others; some are more popular than others; some are mis-identified as others.  Anyway you cut it, you can’t always know immediately what gemstone you are looking at. It takes some expert detective work and the right tools to know for sure. 

Do you have a question about gemstones? Contact us!