There are two kinds of black beads on the market, black agate and obsidian, which are very cheap. Among chalcedony, only agate with clear patterns is generally called agate. The black beads used in a ten-dollar braided bracelet bought by a gold shop are obsidian, and black agate is a little more expensive than obsidian, which means obsidian is cheaper for merchants.

Natural black agate is very rare in the market, because the natural color is impure and there are many variegated colors. The dyed black agate has already been licensed, which is considered natural in the inspection standard. Although the price of black agate is similar to that of obsidian, at present, most black agates in the agate market are artificially discolored at high temperature, and the color is thick black, which is easily confused with low-grade gems such as obsidian.

Extended data

Obsidian can be processed into handicrafts. In addition, obsidian has the characteristics of glass, and its cross section is shell-shaped and very sharp. In the ancient stone age, it was used as cutting tools such as knives and arrows. Modern people use obsidian as a scalpel blade for surgery. When obsidian is heated above 65,438+0,000℃, it will become white particles with loose and porous texture due to the loss of water contained in it.

Identification method

1, ordinary obsidian without rainbow eyes, is to look at the light under strong light, and the beads are still black without any other reflection. If the pendant is transparent, the light is yellow and dark green.

This obsidian has the largest output, but the lowest market value, so it is generally used for large-scale carving. There are few such fakes in the market, but there are also some unscrupulous merchants who use stained glass as accessories (the most common ones are small brave pendants, with retail prices ranging from a few to a dozen pieces) and inferior Blackstone as accessories (generally large carvings, characterized by many gray spots/spots/stripes under the light). It is difficult for non-professionals to distinguish between these two kinds of fakes. You can use strong light to see if it is yellow.

2, rainbow eye (light) obsidian, that is, you can see the green/purple/yellow reflection when you look under strong light, or in the sun, or under the flashlight of your mobile phone. Among them, the rare quality surface will have light red-eyed obsidian, light blue-eyed obsidian, red-blue obsidian and other multicolor obsidian, and the quality is very rare. A large number of rough stones can only select a small amount of this quality, so it is rare.

Baidu Encyclopedia-Obsidian