So, you have a pretty stone, and you want to know just what it is you have! Maybe it’s a diamond gem stone, or an emerald gem stone, or maybe it’s a close cousin, or even a piece of colored glass. That’s where the science, (and art) of gem stone identification comes in.
Take the ruby, for instance. It’s a deep red crystal, very hard and very beautiful. And very hard to distinguish from its mineralogical cousin, the very beautiful but somewhat less rare spinel.
Chemically very similar, containing only one extra ingredient in its molecular mix, those who would be experts at identification of gem stones have often mistaken the spinel for the ruby. The most famous case of mistaken identity is the Black Prince Ruby, actually a 170 carat spinel, which has been for centuries a part of the Crown Jewels of England.
So, how does one go about identifying gem stones?Well, it takes some training, some special tools, and a lot of patience.
Identifying Gem Stones – Step 1:
First, try to make sure that, the gemstone that you have, is a gem stone. Some times what you think may be a gem stone is just a pretty rock or a piece of metallic ore.
Since the term gem stone is largely arbitrary, this can be hard. Some basic guidelines include:
- If it’s rough and sandy, it should not be identified as a gem stone, no matter how pretty it may be.
- If it’s malleable, that is easily able to be shaped by hammering, crushing or bending; it is probably a metallic ore. Gem stones are primarily identified by a crystalline structure, which can be shaped, but not easily shaped and then only by cutting, fracturing or abrasion.
- A pearl, though used in jewelry, is not considered a gem stone. (Though if you want to identify it as a gem stone, go ahead. I won’t tell anyone.)
- It is tempting to identify fossilized wood as a gem stone because of its shiny, lustrous surface and its attractive lines and colors, but it is not considered a gem.
Identifying Gem Stones – Step 2:
In the identification of gem stones, hardness is one of the most important of all tests. While not usually a definitive way to identify a gem stone, it does at least put you into the correct group of possibilities.
To help you use hardness to identify a gem stone, there are a variety of hardness scales that you can use. The most common is the ‘Mohs’ Scale’ which ranks mineral hardness on a scale of one (talc) to ten (diamond).
To measure the hardness of the gem stone you wish to identify, you will use a hardness kit. This contains a set of substances of varying hardness keyed to one of the hardness scales.
If your test substance can scratch the subject gem stone, then the test substance is harder than the subject gem stone. By trying several test substances on your subject gem stone, you will be able to approximate the hardness of the subject.
Since diamond is often too expensive for most kits, glass is sometimes used in its place.
Identifying Gem Stones – Step 3:
This refers to the tendency of crystals to break along fixed planes in their structure. By striking the crystalline gem stone, you can examine the break and compare it to various cleavage charts.
Many gem stones, including quartz and mica, are easily identified by this way. If you suspect that your gem stone is extremely valuable, like a diamond, you may want to skip this step.
Identifying Gem Stones – Step 4:
This is a method of gem stone identification that involves using the subject gem stone to make a mark on a hard, ceramic plate. Many (but not all) gem stones will leave a streak. By comparing the appearance of this streak to various charts, you have another clue to use in gem stone identification.
Identifying Gem Stones – Step 5:
Crystal morphology, or shape.
Most gem stones are made up of crystals, each with a unique shape based on their atomic and molecular structure. A simple example of crystal shape can be seen by examining sugar crystals and salt crystals under a powerful glass. While they may look the same in a bowl, up close their crystal shapes are very different and unique.
Identifying Gem Stones – Step 6:
While this may seem the first test to use when classifying a gem stone, using color to identify a stone is not as reliable as you might think.
Most people view the sapphire as blue, but this cousin to the ruby can be found in various shades including pink, green, yellow and almost transparent.
The classic diamond, with its colorless crystal, looks so much like the less rare cubic zirconium or cubic zirconia, that they almost indistinguishable without a close examination.
Identifying Gem Stones – Step 7:
Chemical and Physical tests:
These methods of identification of gems most often used by experts because they usually require special equipments. The tests include:
Once you have your list of measurements, and a reliable set of tables for comparison, you are well on your way to identification of your gem stone.
BUT, before you put the down payment on that hunk of magic, check with an expert gemologist to make sure that the shiny stone that you have, is really a diamond, and not a zirconium.
Note: Please don’t try to identify a gem stone by yourself if you have precious/expensive stones. It’s better to check them by a gemologist, to prevent damage to your stones, and for accuracy.