You can quickly identify most gemstones by observing a few basic characteristics, like color and heft. If you want a more thorough, accurate identification, though, you will need to use special tools to examine the interior of the stone.

 

Invest in a gemstone identification chart. If you think you'll be identifying gemstones often, it would be in your best interest to invest in a printed chart or reference manual.

Feel the stone's surface. A stone with a rough or sandy texture should not be identified as a stone.

Know which materials are not classified as gemstones. In particular, pearls and fossilized wood can be mistakenly classified as gemstones but do not fit the qualifications in the strictest sense of the term.

Watch out for synthetics. Synthetic stones share the same structure, chemical composition, and physical properties of their natural counterparts, but they are created in a lab rather than made naturally. You can usually spot a synthetic by observing several characteristics.

  • Synthetic stones often have curved growth patterns inside the stone rather than angular growth patterns.
  • Gas bubbles are that are round and come in large strings are often an indication, but be careful, since a gas bubble in an inclusion can occur within natural stones.
  • Platinum or gold platelets can stick to synthetic stones.
  • Fingerprint-patterned inclusions are common in synthetics, as are nail-shaped inclusions, chevron (v-shaped) growth patterns, wispy veil-like inclusions, and interior columnar structures.

Watch out for imitations. An imitation stone is a material that looks like a real gemstone upon first glance in spite of the fact that it is made of a completely different material. These stones can be natural or artificial, but there are a few good techniques used to spot them either way. Pay a special attention while checking Turquoise, Lapis, Sapphire, Ruby and Emerald because there are many treatments available in market which make the stones same like natural

  • The surface of an imitation may look pitted and uneven, like an orange peel.
  • Some imitations have swirl marks known as "flow lines."
  • Large, round gas bubbles are common within imitations.
  • Imitations tend to feel lighter than their natural counterparts.

 

Some stones can check buy using specific way test .

 

Baltic Amber 

Many people want to be sure that they are buying jewelry made from real Baltic Amber because other types or fakes doesn’t contain Succinic Acid, which is responsible for health benefits of this jewelry. The most common methods for testing this natural resin are listed bellow.

1. Visual amber test.

One of the first things you can do when testing Amber and jewelry made from it is to test it visually. Real Amber beads tend to be unique in their appearance so you should look for imperfections when inspecting them. Some common imperfections are tiny cracks or small air bubbles. Also beads should vary a little in size and its shape shouldn’t be always round. When you touch Amber it tends to be a little warm, which is not the case with most other fakes.

2. Salt Water test.

The other effective test for identifying real Amber from fake is Salt Water test. In order to do this test you will need about 7 teaspoons of salt and a medium size cup of water. Add all teaspoons of salt into the water and stir well until salt is fully melted. In the next step add your Amber gemstone into this water. Real Amber should float in this water easily while majority of fakes will sink fast. The main drawback of this method is that it is not very suitable for testing Jewelry that has some metal or other components in it; however it works well for loose beads.

3. Rubbing test.

One of the simplest ways to distinguish Amber from Copal is to do Rubbing test. Since real Amber has electrostatic properties it can pick up tiny paper pieces or dust when it is charged sufficiently. So in order to charge Amber you need to wrap it in a cloth and then rub it for some time (20-60 seconds). In the next step hold this gemstone near a strand of hair. If your hair is attracted towards this stone it means that static was produced and most likely you are holding real Amber. Alternatively if this gemstone didn’t became charged but rather sticky it means that it is Copal.

4. Hot Needle test.

One more way to differentiate genuine Amber from fake is Hot Needle test. To perform this test you need to heat the needle and then push it against the stone. In case the needle went in only slightly or some cracks were left it means that it is most likely real Amber. Also if it is genuine Amber you should also notice a smell similar old punged tree. When doing the same test with fakes the needle goes in very easily and the smell is either plastic or fresh pine (Copal). The main disadvantage of this test is that it might leave a small mark, which is caused by burning.

5. Scratch test.

Scratch test is usually preferred when not expensive Amber is being tested. This is mainly because scratching on this gemstone can potentially damage it. Doing this test can help to separate colored glass from Amber. This test is useful because glass beads can’t be scratched while using metal and real Amber is soft enough so its beads can be scratched on. So basically if you can scratch on your jewelry bead it is most likely Amber and if you are not able to do this then its probably a fake.

6. Scent test.

This test might be a bit too difficult for individuals who are not very familiar with this natural resin. This is mainly because you need to know how the difference between smell of Copal and Baltic Amber. Scent of true Baltic Amber tends to be stronger than compared with Copal. And in case you are dealing with other type of fake you should smell plastic smell once a bead is heated.

7. Acetone/Alcohol test.

Rub a small area with nail polish remover or acetone.  Real amber will not be affected by the solution, while copal and other amber substitutes will become tacky/sticky.

*Note – This method will damage pieces which are not amber.

8. UV light test.

True amber will fluoresce under a black light.  From the research I’ve done, what color and how much it glows depends on the type of amber.  Some pieces will glow brighter than others and in different shades of yellow-green to blue.

*Protect your eyes from the UV Light!

Before choosing one of these tests it is important to keep in mind that some of them might leave marks or ruin your Amber gemstone.

I just give few tips , but when you going buy specific stone can find online to read tips or video .
I hope it will be helpful for you