You can identify most gemstones quickly by paying attention to some of their basic characteristics, such as color and weight. However, if you want to make a more thorough and accurate identification, you will need to use a special tool to examine the inside of the stone.
Step
Use Identification Map
Step 1. Purchase a gemstone identification map
If you feel that you will often identify gemstones, then you should purchase a printed chart or reference guide.
If in doubt, look for a book or chart provided by the Gemological Institute of America (GIA)
Step 2. Search for a base map online
If you only need to identify gemstones occasionally, do so by looking at online gemstone charts. These online charts are a little less detailed and extensive, but at least they can still be useful.
- The Hiddenite Gems' identification map can be used when you know the color and hardness of the stone:
- The Gem Select RI map can be used when you know the refractive index and double-refraction of the stone:
- The American Federation of Mineralogical Societies (AFMS) offers Mohs' Scale maps for free:
Method 1 of 3: Make sure that the stone is a gem
Step 1. Feel the surface of the stone
Stones that have a coarse or gritty texture are not identified as gemstones.
Step 2. Check the malleability
Stones that are malleable-for example, are easy to hammer, crush or bend-they look more like metallic ore than actual gemstones.
Real gemstones have a solid structure. The structure can be formed by cutting, dividing and sanding, but the structure has a fixed plane that cannot be changed by pressure alone
Step 3. Know which materials are not classified as gemstones
Pearls and wood fossils may be classified as gemstones arbitrarily but do not qualify in terms of precise terms.
Step 4. Beware of synthetic rock
Synthetic rocks have the same structure, chemical composition and physical form from natural rocks, but synthetic rocks are made in a laboratory rather than made naturally. You can identify synthetic rocks by observing several characteristics.
- Synthetic rocks often have a developmental pattern that bends within the rock rather than an angular pattern of development.
- Gas bubbles that are round and appear in strands can be seen, but be careful because they can appear in natural rock.
- Platinum or gold plates can stick to synthetic rocks.
- Fingerprint patterns are generally found in synthetic rocks, such as nail shape, chevron or (v) shaped development pattern, hair shape that is not very clear, and columnar interior structure.
Step 5. Watch out for artificial rocks
Artificial stones are made of materials that at first glance are similar to real gemstones even though they are made of completely different materials. These rocks can be formed naturally or artificially, but there are some good techniques for identifying them. Pay attention when you examine turquoise, lapis, sapphire, ruby or pomegranate and emerald as there are several treatments available in the market to make the artificial rock the same as natural rock
- The surface of the fake rock looks mottled and uneven like an orange peel.
- Some other imitation rocks also have circular markings known as "current lines."
- Large, round bubbles can be found in the faux rock.
- False rock is usually lighter than natural rock.
Step 6. Determine whether the gemstone is an assembly stone or not
Assembled stone is made of two or more materials. These rocks may contain all natural rock, but often contain synthetic materials mixed in.
- Use a light pen to illuminate the rock as you check for signs of assembly.
- Look for the difference between colored and colorless sparkles or cement.
- Also look for "red ring effect." Look for a red ring along the outside of the rock. If you find a red ring, it is certain that the rock is assembled rock.
Method 2 of 3: Part Two: Making Basic Observations
Step 1. Pay attention to the color
The color of the gemstone is often your first clue. This component can be further divided into three parts: hue, nature and intensity of color.
- Do not shine a light on the rock to check the color of the stone unless you have dark rock and need to determine if it is black, dark blue or some other dark color.
- Hue or color pattern is the overall color of the rock body. Get as specific as possible. For example, if the rock is yellowish green, don't just call it "red" rock. GIA divides the color of the stone into 31 different color shades.
- Tone is a color property that determines whether the color is dark, medium or light or somewhere in between.
- Saturation is the intensity of the color. Decide whether the tones are warm (yellow, orange, red) or cool (purple, blue, green). Check the brown color for warm rocks. Check the gray color for cool rocks. The more brown or gray the rock you are examining, the less intense the color will be in the rock.
Step 2. Observe the translucency of the rock
Translucency describes how light penetrates through gemstones. A rock can be transparent, translucent or opaque.
- Transparent rocks are completely translucent (example: diamond).
- Translucent rock is translucent, but some colors may change (example: amethyst or aquamarine).
- Impermeable rock cannot be penetrated by light (example: opal).
Step 3. Check the specific weight or gravity
You can determine how heavy the rock is by tossing it in your hand. This method is the fastest and easiest way to calculate the weight of rock without having to perform specific gravity tests and equations.
- Throw the rock in the palm of your hand to determine the weight of the rock and then ask yourself if it feels heavy for that size, feels heavier or feels unusually lighter.
- Specific gravity readings are an old fashioned way among gemstone experts, while weight measurements are used as an accurate estimate.
- For example, aquamarine rocks are light in weight, while blue topaz, which has a similar appearance to aquamarine, has a high or heavy load. Likewise, gems also have a lighter weight than synthetic zirconia.
Step 4. Pay attention to the cut
While there is no foolproof identification method, some gemstones are most likely cut in a certain way. The ideal cut is often determined by the way light reflects off the stone structure.
The most commonly recognized cutting styles are facet, cabochon, cameo, bead, and tumbled. Of the many popular cutting styles, you will also usually see substyles
Method 3 of 3: Studying Gemstones in Detail
Step 1. Ask yourself whether you need to do a crash test or not
There are several identification tests that you may want to avoid if you want to keep the gemstone. This includes hardness, streak and cleavage tests.
- Physically, some stones are harder than others. Hardness is usually measured by the Mohs' Scale. Use the various materials available in the hardness meter to scratch the surface of the gemstone. If the surface can be scratched, then the stone is softer than the object being scratched. Conversely, if it cannot be scratched, then the material is harder than the object being scratched.
- To test the streak, drag the stone across a ceramic plate. Compare the doodles that are left with those illustrated on the doodle map.
- Cleavage is concerned with the way a crystal breaks. If there are chips along the surface, pay attention to the area inside the pieces. If not, you'll need to bang the gemstone until it breaks. Notice if the area is round like a seashell ring (conchoidal), straight, grainy, flaky or uneven.
Step 2. Check the optical phenomena
Optical phenomena only occur in some rocks. You can observe color changes, asterisms, moving light pools, etc.
- Examine optical phenomena by shining light using a light pen along the rock face.
- Color change is one of the most important optical phenomena to look for. Each stone should be checked for discoloration. Look for color changes between natural light, incandescent and fluorescent light.
Step 3. Notice the sparkle
Gloss is the quality and intensity of the surface of the stone in reflecting light. When testing luster, reflect light from the best-polished part of the gemstone.
- To test for sparkle, reflect light on the surface of the stone. Look at it with the naked eye and use a 10x magnifying glass.
- Determine if the stone looks dull, shiny, metallic, shiny (shatterproof), looks like glass, is greasy or smooth like silk.
Step 4. Pay attention to the dispersion of the gemstones
Dispersion is the way a stone refracts white into a spectrum of colors. The visible dispersion is called fire. Pay attention to the number and strength of the fires to help identify stones.
Shine the light from the light pen on the surface of the stone and then notice the fire within the stone. Determine if the fire is weak, medium, strong or very strong
Step 5. Determine the index of refraction
You can perform a refractive index (RI) test using a refractometer. Using this tool, you can measure the degree of light refracted within the rock. Each gemstone has its own refractive index, so knowing a sample of the refractive index can help you determine the type of rock.
- Place a drop of refractive index liquid on the metal surface of the refractometer near the back of the crystal hemicylinder (the window where the stone will be placed).
- Place the stone on top of the liquid and slide it into the center of the hemicylinder crystal with your finger.
- Look through the observer's lens without magnification. Keep watching until you see a line of bubbles, then pay attention to the bottom of the bubble. Take the reading, then round the decimal to the nearest hundredth.
- Use a magnifying lens to take a more specific reading and round the decimal to the nearest thousand.
Step 6. Consider doing a double-bias test
Double refraction is related to the refractive index. When you perform a double refraction test, place the gemstone on the refractometer six times during the time of observation and record the changes that occur.
- Perform the standard refractive index test. Lay the stone gradually up to 180 degrees, turning 30 degrees in each turn. Take refractive index readings every 30 degrees.
- Find the difference between the lowest and highest readings to determine the stone's double refractiveness. Round to the nearest thousand.
Step 7. Check for single and double refraction
Perform the test on translucent and transparent stones. You can determine whether the stone is single refractive (SR) or double refractive (DR). Some stones can be classified as aggregate (AGG).
- Turn on the light of the polariscope and place the stone over the bottom word lens (the polarizer). Looking through the top lens (analyzer), rotate the top lens until the area around the stone is darkest. This is your starting point.
- Rotate the analyzer 360 degrees and watch how the light around the rock changes.
- If the stone appears dark and remains dark, then the stone is single refractive (SR). If the stone starts to glow and remains luminous, then it is an aggregate (AGG). If the light or darkness of the stone changes, then the stone has a double refractiveness (DR).
Tips
- Clean the gemstone with a gem cloth before you test it. Fold the fabric and place the gems in it. Gently rub the stone between layers of cloth with your fingers to remove dirt and grease.
- Hold the stone with tongs as you test it to prevent grease or smearing.
