The difference between platinum and similar metals1

Platinum is distinguished by its silver-white color and streaks, hardness 4～4.5, specific gravity 15-19 or 21.4, stable chemical properties, insoluble in common acids, and easy to distinguish from similar metals. 1. The distinction between platinum and silver. Platinum and silver jewelry is very popular in the market and has always been a favorite of many women. Platinum is distinguished by its silver-white color and streaks, hardness 4～4.5, specific gravity 15～19 or 21.4, stable chemical properties, insoluble in common acids, and easy to distinguish from similar metals. 1. The distinction between platinum and silver. Platinum and silver jewelry are very popular in the market, and they have always been the favorite jewelry of many women. Since platinum and silver have many similarities, it is necessary to distinguish them. Platinum and silver are distinguished by hardness, specific gravity, and chemical stability. Generally, the following simple methods are used to distinguish. ⑴. Comparison of color and hardness. Platinum is silvery white or off-white; the texture is harder, with a Mohs hardness of 4 to 4.5. Silver has a pure and white color; its texture is smooth and delicate, with a Mohs hardness of 2.5-2.7, which is softer than platinum and can leave traces when scratched with a fingernail; it has no elasticity, and the foil is easy to bend by hand and difficult to restore. ⑵, test specific gravity The density of platinum is high, and the specific gravity is high. Although silver is silvery white, its relative density is 10.53g/cm3, and its specific gravity is 10-11, which is only 1/2 of platinum. The same volume of silver is half lighter than platinum. Generally, platinum and silver can be roughly distinguished by weighing by hand. (3) Chemical method Silver is chemically unstable, soluble in nitric acid, and emits nitrogen dioxide gas. Platinum is insoluble in nitric acid and can dissolve quickly in heated aqua regia. Its dissolution rate is extremely slow at room temperature, and it is generally difficult to detect with the naked eye. Place the platinum crumbs on the touchstone and drip a little mixture of nitric acid and hydrochloric acid. If the debris still exists, it is platinum; if the debris dissolves and disappears, it is silver. 2. Distinguish from metallic lead and aluminum Platinum is distinguished from metallic lead and aluminum by different deformation characteristics and specific gravity. Metal lead and aluminum are inelastic and cannot be restored after deformation; and their specific gravity is much smaller than platinum. The specific gravity of lead is 11.36 and the specific gravity of aluminum is 2.7, which are about 1/2 and 1/8 of platinum respectively. Can be distinguished. 3. The difference between platinum and platinum Platinum is an element, while platinum is a mixture. Platinum: Platinum (pt), chemically more stable than gold, and more expensive than gold, it is used to make high-end jewelry. The'pt900' or'pt950' seen on the products of the jewelry store means that the platinum content in the jewelry is 90% and 95%, respectively. The common name of platinum is platinum, which is pure white. The reserves of platinum in nature are rarer than gold, so its price is more expensive than gold. Platinum can maintain the original color of white-precious diamonds and is very strong. It is the best material for inlaying diamonds. It is diamonds that make platinum a superstar of precious metals for jewelry. Most of the finenesses used in jewelry inlays in my country are pt950 and pt900, and pt900 is the most commonly used. The platinum content in platinum alloy jewelry in the 'Regulations and Naming Methods of Purity of Jewelry and Precious Metals' stipulates that the total content of platinum and palladium shall not be less than 950% Platinum jewelry is crowned platinum or pt in terms of purity per thousand. Example: 990, pt990 or foot platinum. Pure platinum is relatively soft. If it is to be inlaid with diamonds, it must be formed into an alloy. Even if 5% of the alloy is added, the pt can be hardened to meet the processing requirements. Part of the added alloy components must be platinum group metals. The purity allowed in Japan is 1000.950.900.850, and there can be a slight (0.5%) negative difference. Purity of 850pt is generally used for chains, and pt900 is the most commonly used purity. Since Japan is Hong Kong's most important export market, Hong Kong adopts Japanese standards. The United States stipulates that if the purity is called pt, it must contain at least 50% platinum, which is a total of 95% platinum group metals. The purity of platinum content higher than 95% can be marked with pt. Jewelry with platinum content between 75%-95% must also be marked with platinum group metals. Jewelry with platinum content between 50%-75% must be marked with the name of the platinum group metal and its content. Such as 585 platinum and 365 palladium (585plat365pall). Only the United States allows k platinum alloys. The specific gravity of platinum-palladium alloy: pt950---20.64 pt900---19.88 pt850---19.18 k The difference between platinum and platinum. Strictly speaking, k platinum cannot be equal to platinum. Platinum is a kind of precious metal that is naturally white in itself. It is currently the most expensive of all precious metals in jewelry. Commercially available platinum jewelry has the'pt' mark, which is the English abbreviation for platinum. K platinum is a white alloy made by smelting gold and other metals. The so-called 18k platinum is actually synthesized from 75% gold and 25% other metals. Therefore, k platinum can not be marked with the 'Pt' mark, but can only be marked with gold and purity according to its purity. For example: 18k platinum can only be marked with '18k' and'g750'. So, how to distinguish the two simply? First of all, you must go to a large shopping mall to buy these precious jewellery. The most important thing is to read the label clearly and see if the jewelry is marked with'k' or'pt'. When buying platinum jewelry, you should ask the operator to issue an invoice. Write clearly on the invoice whether it is platinum or white 18k gold. It is best to indicate the weight of the jewelry, so that it is easier to claim for fraud in the event of fraud. Previous: The history of platinum Next: The application and value of platinum