How to Identify (Test) the Gemstones

Gems are expensive, and with over 200 varieties of gemstones available, it is very important to identify the gemstones carefully before paying a great deal of money and wearing them. Gemstone treatments or enhancements are is as old as 2500 years, and it refers to the way to fix the impurities natural gemstones may have while procuring these. Most of these treatments are accepted norm in the industry and improve the aesthetic appeal of gemstones.

At the same time, there is a huge gap between demand and supply of the gemstones and everybody is looking for genuine ones. To fill this gap market is flooded with synthetic or imitated gemstones which look like almost genuine, and sometimes more than genuine, which make it almost impossible to differentiate from a genuine gemstone without the expert and skilled help. You are never sure if you are paying price for merely a piece of artificial jewel. Judging a gemstone is not possible for a common man with naked eyes. Only highly qualified astrologers or certified laboratories can differentiate among these gems.

Synthetic vs Imitation Gemstones

Synthetic stones are created in lab like places, and share the same gem structure such as chemical composition and physical properties of their natural counterparts.

Whereas an imitation stone, also looks like a real gemstone, is made of a completely different material with different composition and physical properties, but looks like genuine.

Gemological Tools to Identify Gems

There are a few gemological tools and procedures to reliably detect signs of heat treatment, fracture filling, radiation treatment, and beryllium treatment etc. These include:

10x Triplet Jeweler’s Loupe

This is perhaps most popular gemological instrument. You can do a complete diamond analysis with just this loupe. This tiny tool is easy to carry anywhere in your pocket.

Gemological Binocular Microscope

Microscope is very good for extensive research of gemstones. However, its usage requires specific conditions, you cannot carry this everywhere, and moreover it requires to be plugged in to work.


This is a quite simple hand held tool which requires a little bit of training to use. A trained gemologist with spectroscope will be able to see the right details of the gemstone that allows for identification.


It is one of the most important tools. To get the most from its testing ability, it requires little bit of training to identify and judge and gemstone through refractive index and optic character.

Refractive Index Liquid

It is gem testing liquid with a high refractive index (RI) used along with Refractometer.


The polariscope is also very efficient tool which allows you to view the optic character of the gemstone making gemstone identification far more accurate and efficient.

Gemstone Identification Criteria

Gemstones are tested according to the following physical and optical properties.


Luster is a way gemstone reflects light. It is perhaps first thing gemologist do the check the stone through light. There are three types of luster- metallic, glassy and dull.


Standard 10-point Mohs hardness scale is the perfect way to examine the hardness of the gem and identify accordingly.


The separation of white light into spectral colors is called dispersion. Illuminate the gem and examine the amount of colors it is reflecting, and if it is weak, moderate, or strong. The strength of these colors will help to identify the gem.


Heft refers to the comparative study of weight and size of the gem. Stones made of different materials will have a low heft.


Transparency is and ability of gemstones to transmit the light.


Color is perhaps one of the most important and difficult factors to identify the gem. Only experts can identify the real color of the stone. Color could be the result of a chemical impurity.


Streak is another form of color identification and somewhat more easy and reliable. Scratch your mineral across the streak plate and review its color.

Crystal Form and Mineral Habit

Mineral habitat is another important factor to identify the nature of gem. Some gem origins are very famous across the world and add into the credibility of the gem.

Cleavage and Fracture

Cleavage is the fracture in mineral, or a way mineral breaks in. Minerals break in many forms and cleavages such as one cleavage, two cleavages, three cleavages etc. Carefully break the mineral to observe the shapes and angles of the fractured pieces to identify the gem.


Each gem has magnetism in it either less or more. It is an important factor to consider the real nature of the gem.

Chemical and Physical Tests

There are a few other methods of identification of gems such as Specific gravity, Refractive Index, Light Dispersion, Color changes etc. These methods are mostly used by the experts. Sometimes more than one test is required to identify a gem. Only a well-trained gemologist with experience can provide detailed information about a gemstone.

How to Identify Pukhraj (Yellow Sapphire)

A genuine yellow sapphire should not have scratches or bubbles inside it. Genuine yellow sapphire is very hard and cannot be scratched easily, only diamond can scratch it.

It is well known test to keep yellow sapphire in milk for a day, if it doesn’t change any color then it is surely genuine.

How to Identify Moonga (Red Coral)

Keep the coral in a glass of milk; if color of milk is changed to red, coral is genuine. This happens because genuine coral radiates red color which is absorbed in the milk.

Genuine coral is sensitive to the health. If you are wearing a genuine coral then the stone will fade color before your health problem appears. It gets the original color back when you recover from your health issues.

Rub the stone against the raw turmeric. The genuine coral will not leave red marks on the turmeric.

How to Identify Diamond (Heera)

Put the diamond in front of your mouth and fog it, a real diamond disperses the heat from your breath.
Turn the diamond upside down on a piece of newspaper. If you can read print through the stone probably it isn’t a diamond.

Drop the stone in a glass of water, a real diamond will sink.

Heat up the diamond with a lighter for 30 seconds, and then drop it into the cold water. Real diamond is strong enough that it will not shatter

How to Identify Pearl (Moti)

Real pearl is cold to touch for the first couple of seconds.

Most real pearls are rarely rounded; if it is real, and it is round then it will command an extremely high price.

Real pearls seem to be heavy in weight as compared to fake ones.

How to Identify Emerald (Panna)

Genuine emeralds are not perfectly clear as they have natural imperfections such as lines, bubbles, crystals, etc.

Fake emeralds usually look perfect and clean, and they are relatively cheap.

Exposing an emerald to light can also tell if gem is real, real emerald doesn’t exhibit intense colorful flashes.

How to Identify Ruby (Manik)

It is said if you place an original ruby on an un-blossomed lotus bud it will blossom in a short time.
If you place a real ruby in a glass jar, a red hue of light will emit from the jar.

Scratch the piece of porcelain or glass with ruby, if it is original it will make a scratch mark, if it is fake, it will leave a red mark.

Also, try to scratch the ruby with a coin, a piece of glass, a steel knife or sandpaper, if any of these can scratch the gems, it is surely not original as original ruby can only be scratched by diamond, sapphire, or another ruby.

How to Identify Blue Sapphire (Neelam)

Neelam is very fast acting gem, and therefore requires more precautions.

Keep the blue sapphire in a glass of milk for 24 hours; it should not change the color if genuine.

Carefully observe the color of sapphire, it should not have two tone colors, or any spot in it. Genuine sapphire is so pure that the light can pass thorough it easily.

This is well known concept to keep the neelam under the pillow for a few days before wearing, and observe what kind of dreams you have, you will have bad dreams in case it will not suit you.

These are just preliminary tests as per the popular assumptions, one should not rely on these completely. Gems must be checked in laboratory for further confirmation.

Gautam Trehan

Would love to hear from you! You can write/ask me anything! at [email protected] Happy Reading!