1, see the qualification certificate
First of all, look for the qualification certification of certification bodies, generally including CAL certification, CMA certification, CNAL certification, CNAS certification, ILAC-MRA certification, which are all authoritative qualifications. The contact information of the institution must be printed on the back of the certificate. In addition to the qualification of the institution, there must be detailed information such as the name, contact number, address and website of the appraisal institution.
2. Look at the exam content
The testing contents include the name, color, purity, total mass, density, refractive index and other items of jewelry, and these items are very strict in the national certified jewelry and jade testing institutions.
3. Look at the signature of the appraiser
The appraisal certificate must be signed by two appraisers to be valid, one is the appraiser and the other is the reviewer.
4. Look at the certificate seal
Jewelry appraisal certificates generally have steel seals. The formal certificate has deep steel seal, clear mark and legible font.
5. Look at this figure.
There is the serial number of this certificate on the back of the appraisal certificate, which should be consistent with the serial number posted on the back of the physical object.
Step 6 investigate
Official website, SMS and QR code scanning are also important methods. Of course, now all appraisal institutions, large and small, can set up their own inquiry systems, and what they can find is unreliable. The query can only determine whether the certificate really comes from the declared organization.
Expand small knowledge
I. Identification of diamonds
1, fog test
Put the jewel in your hand in front of your mouth and take a deep breath. If the fog stays for a long time, a few seconds, it is probably false. Real diamonds dissipate heat quickly and are not prone to fogging. Even if you breathe first and then look, diamonds are still much clearer than fake diamonds.
Step 2 check with a jewelry magnifying glass
Natural diamonds often have some small flaws, which can be seen through a magnifying glass. What you look for through a magnifying glass is a defect formed by minerals, or a very subtle different color. These two phenomena are one of the evidences that diamonds are real. Although this diamond may not be perfect, at least it is true.
Step 3 check the refractive index
The refracted light of the diamond is very sharp and bright, and the light can pass through it without hindrance, showing dazzling brilliance. However, materials such as glass or timing are not smooth because of their low refractive index. The refractive index of stone is extremely difficult to change, even if it is cut professionally, because the refractive index is one of the properties of stone itself. Therefore, by carefully checking the refractive index, the authenticity of the diamond can be more clearly determined.
You can put the diamonds upside down in the newspaper. If you can see the words in the newspaper through the diamond, or even the vague black marks, then this stone is probably fake. Diamond has a high refractive index, so you can't see the writing in the newspaper through the diamond.
Step 4 observe the reflected light
The reflected light of real diamonds will appear gray in different degrees. Looking down from the top of the diamond, if you see the reflected light of rainbow color, then either the diamond is of low grade or it is not a real diamond.
Second, the identification of ruby
1, color
Natural ruby, even pigeon blood red, is not a very pure color, and the formation conditions of gemstones lead to local or a little uneven color. Usually, the genuine natural ruby color is softer and the eye observation is very comfortable; If it is a fake, it will look dazzling.
2. Smooth
Genuine products have a mild and soft luster, showing several different luster, while fake products give off a glass luster. Under strong light, its glass luster is particularly obvious, which is also some unique characteristics of artificial ruby.
3. Production process
Real high-quality ruby, the process is very strict, and every link needs to be strictly controlled. Natural rubies are rare, and artificial destruction is not allowed, so the cutting of real natural rubies is perfect and exquisite, which makes the luster of rubies perfectly refracted. On the contrary, in artificial gem, it is more casual and the cutting is rough.
Third, the identification of sapphire
1, color
Sapphire is characterized by uneven color. You can see parallel hexagonal cylinders, flat bands with different shades and growth lines. Artificial sapphires are of the same color, and their growth lines are arc-shaped strips, and they are often breadcrumb-shaped or beaded bubbles in the body.
2. Strong dichroism
The strong dichroism of sapphire means that it is blue from one direction and blue-green from the other. Different sapphire producing areas have different characteristics, and there are not many sapphire producing areas in the world. Sapphire produced in Myanmar is bright blue and titanium, which can produce six or twelve starlight because of its inclusion. Sapphire from Kashmir, India, is a kind of high-quality sapphire, which is cornflower blue and indigo blue with bright color. In addition, sapphires from other regions also have their own characteristics.
Four. Cat's eye recognition
1, optical band
When rotating the cat's eye, two or three light bands can appear on the arc top of the fake cat's eye, while there is only one real cat's eye. The eyeliner of the fake cat's eye is relatively rigid, while the eyeliner of the real cat's eye is flexible to open and close.
colour
Step 2 color
True cat's eyes are mostly brownish yellow or light green, while fake cat's eyes are varied in color, including red, blue and green. In addition, from the side of the opal with a single light source, the colors on both sides of the opal are different. When the honey yellow opal is illuminated from the left, it is honey yellow on the left and milky white on the right. When illuminated from the right, its color is just the opposite.
Verb (abbreviation of verb) Identification of jade
1, observe the texture.
If possible, you can observe the internal mechanism of jadeite with a magnifying glass of 10 times. If you can see fibrous or granular textures like asbestos intertwined, then this jade may be really nephrite or jadeite. On the other hand, chrysotile is a kind of microcrystal aggregate, which looks uniform under a magnifying glass. If you see a layered texture under a magnifying glass, then your jade may have one or even two layers of other things superimposed on it.
2. Listen to the sound
Listen to the sound of plastic beads knocking on each other first, then find a jade that you have identified as real jade and tap the jade you want to test. If it sounds like a plastic bead just now, then the jade you detected is probably fake. If the voice is deeper and louder than before, it may be true.
Step 3 feel with your hands
Holding jade in your hand, the real jade should be cold and smooth, a bit like holding soap. It will take some time for the real jade to heat up in your hand. This method is especially suitable for identifying jade with the same shape and size.
4. Allergy test
Find a blunt pair of scissors, gently press down on the jade, and then make a small mark. Scratches should be scratched as far as possible at the bottom of the jade to avoid being too obvious. If the surface of jade is elegant, you can't use this method, otherwise it will easily damage jade. If the scratch you draw is white, rub it gently. If there are scratches, then this jade is unlikely to be real.
Jade is very hard. It can cut glass and even metal. Nephrite, on the other hand, is a bit Microsoft, so if the test method is incorrect, it may destroy a real nephrite. In addition, even if the tested jade can cut glass or steel plate, it may only be some particularly hard imitation jade, such as various green jade, prehnite and so on.