The main difference between ruby and other rubies is to test its refractive index and light. Hardness test is suitable for raw stone.
One is to measure its refractive index. Only garnet-like magnesium aluminum garnet has a refractive index of 1.74- 1.75, which is lower than that of Hongbao. Sometimes Fe-Al-Mg-Al garnet may be mixed with rubies made in Thailand, but there is a big difference.
Secondly, except for artificial rubies and tourmalines, other rubies have no two directions. Tourmaline is similar to ruby in two directions, but under the Chelsea filter, tourmaline does not show red fluorescence (note that the redness of a few tourmalines is caused by chromium, and fluorescence reaction can be seen under the filter. But can be distinguished from hardness).
As long as you look carefully, it is not difficult to distinguish the second floor stone. That is, remove the jewelry from the holder, put it in a bottle filled with water, and observe it carefully from the waist of the gem. Because the two layers of stones are made of two kinds of red products, there is a big difference, which is easy to see in the water. In addition, observing the waist with a magnifying glass of 10 times, you can see the bonding lines and bubbles at the bonding place. Another reliability is to measure the refractive index of the next two layers, and the difference is the second layer of stone.
After distinguishing rubies from other rubies, the second step can be carried out, that is, identifying natural rubies and artificial rubies.
The first is to observe carefully with a magnifying glass and find doubts. Then use multi-means and multi-equipment instruments to check. Then the actual natural products and artificial products can be roughly judged by experience according to the feeling at first sight.
If the artificial products are very pure, in the case of good transparency, there will be a fleeting rose color, and natural products are not easy to appear.
In addition, if there are individual independent black carbon spots and patches on the surface or shallow part of ruby raw materials or finished products, they are all artificial rubies.
Furthermore, some natural rubies with white spots and irregularities are genuine.
Finally, the six star lines of the artificial starlight Hongbao antiquities are conspicuous. The star lines extend to the lower part of the gem, and natural white fog can be seen on the surface.
However, even if you have seen the truth, if you can, you must check it carefully with several instruments. Because people's judgment ability is often influenced by many natural and human factors.
The discrimination between ruby and food has been reported in foreign works, and there are also similarities. She measured the highest ruby. But the most important thing is to correctly judge the observed phenomenon, otherwise there will be mistakes.
Natural ruby is a trigonal crystal system, and its growth lines are all straight lines, which are parallel to the crystal plane and intersect with the straight line, and the intersection angle is 120 degrees. Artificial products grow in an inverted pear shape. Therefore, it is a dense bending pattern, much like the groove pattern of a record.
If the growth line cannot be observed with a magnifying glass, pure diiodomethane can be used as the immersion liquid (the refractive index is similar to that of ruby). Put a developing photographic paper on the bottom of the bottle containing diiodomethane solution, put the top face of ruby down on the photographic paper, and use appropriate lighting. If the development is correct, even transparent corundum-free lines will appear (which should be carried out in a dark room), which is one of the most reliable identifications.
Ruby is rarely complete, and usually contains small crystals of other minerals and fine needle-like red rutile reflective fiber bundles. Some small holes and irregular fragments containing liquid can be observed. Observing with a magnifying glass or microscope, all the contents can be seen as genuine. But be careful not to mix it with the dark crystal impurities of artificial ruby and the spherical or slender bubbles commonly found in artificial products. Such bubbles are rare and sometimes appear in groups. If you look at it with light, you can see that it is white and reflective, very bright. Although it is difficult to distinguish it from natural products, it is easy to distinguish it with more experience through long-term observation.
Natural rubies often contain a large number of trace elements that cannot be prepared artificially, which inhibits the penetration of short-wave ultraviolet rays into natural rubies. Artificial rubies with pure short-wave ultraviolet rays are easy to penetrate. Using this principle, we can put a piece of developing photographic paper in a flat water bottle, a ruby under the photographic paper, a short-wave ultraviolet lamp 20 cm away from the ruby, and expose it in a dark room for a few seconds. As long as the exposure is accurate, the natural ruby is white on the developing photographic paper, indicating that ultraviolet rays do not penetrate. Man-made products are dark, with only a white circle on the edge, indicating that ultraviolet rays can penetrate.
When cutting and grinding natural rubies, in order to get the best, the table must be perpendicular to the optical axis of rubies, so it is single refraction from the top of rubies.
On the other hand, the workpiece can observe a strong bidirectional direction from the top. However, in some backward areas, in order to maintain the maximum weight of rubies, the direction is not considered when polishing. Therefore, this identification cannot be used alone to distinguish authenticity.
There are clusters of natural products with different shades or accompanied by different shades, which can be regarded as genuine products. At or near the junction of artificial ruby facets, common crack marks, called burn marks, are caused by local overheating during polishing. When cracks are found by careful observation, other inspections must be carried out.
The natural ruby produced in Myanmar has no phosphorescence when observed by ultraviolet lamp or cross filter. Artifacts will have phosphorescent residual light for a period of time (in a dark room).
However, a few natural products will also have short-lived phosphorescence, so we should pay great attention to the difference. Natural rubies made in Thailand have no fluorescence and need more tests.
Because most rubies have fluorescence reaction, foreign jewelry stores often install ultraviolet devices, so that rubies can find a beautiful light like fire, and buyers can't put it down. But the takeaway shop is far less brilliant than the store. Therefore, if you buy rubies in this situation, you must take them outside the store and observe them in the sun before buying them.