In the manufacture of jewellery using metal materials, non-metallic and some accessories. Among the used metals are most popular, no doubt, remains the gold. The quality of gold is determined by assay, showing its content in one kilogram of alloy. For example, a sample of 585 says that in one kilogram of an alloy contains 585 grams of gold. The remaining 415 grams have actual metals. Thus, the jewelry 585-carat gold contains 58.5 per cent. Why is jewellery not made of pure gold? The fact that pure gold 999-th sample is a fairly soft metal and easily deformed, so the products made from it are fragile. When you add in the gold and other metals, the resulting alloy becomes more solid. Supplement to gold other metal not only increases its strength but also changes color. If the added copper, the gold acquires a reddish or pink hue, the presence of silver gives a yellow hue, and palladium, zinc or Nickel gives the gold a white color. Sometimes I use such rare metals as iridium, osmium and ruthenium – they increase the hardness of the alloy without color change. To determine the quality of gold in terms of its color very difficult. Buying, for example, somewhere in Turkey, 14-Karat gold (the equivalent of 585-th sample), you can after some time to notice that it went dark. This suggests that the real test of this jewelry is not above 375. Of course, for the production of jewelry is used not only gold but also other metals – particularly silver and platinum. Silver jewelry is better to buy not lower than 900-th sample. Platinum jewelry is used by higher 950-th sample. In addition to metals, for the production of jewelry widely used precious and semiprecious stones. Usually when you use gems they constitute the bulk of the cost jewelry. The most valuable are diamonds, rubies, emeralds, sapphires, alexandrite. Semi – precious stones-aquamarine, Topaz, tourmaline, amethyst, rock crystal, turquoise and many others, only about two dozen names. Its value is second only to precious stones. Semi-precious stones – agate, onyx, lapis, malachite, jade, carnelian and others. Usually they are opaque or polupronicaema, is widely used in the manufacture of jewelry. Mention should also be made of organic stones such as pearls, amber, coral, mother-of-pearl.