When we speak about valuable metals, there are only a few elements that come to mind and these are silver, platinum, and gold. The luster of gold has attracted people back in the olden times. Gold is a sign of vanity and luxury and that is why it is used to make rings, bracelets, chains, and embellishments on garments. Because it is such an important metallic element, being a royal metal that it is, many false gold jewelry items have arisen. There is no way to eliminate fake gold in the market but there is a way to find out if a piece of gold is real or counterfeit.
What many don’t know is that usable gold does not really come pure because pure gold is soft and weak. It used to make jewelry is alloyed with other metals, such as silver, platinum, and copper. You may be familiar with the term karat or carat in gold. It is a special unit of measurement used only for gold. One karat means that 1/24 of an object is gold. So when you come across something that is 24 karats, you have come across an object made of pure gold. Gold jewelry items come in different karatage from 8 to 24 karats. The karatage is part of the hallmark of the gold piece and you find it as a tiny imprint. Generally, as the amount of gold increases and so does its karatage, its value also increases, regardless of the flaws on the gold piece Vàng 10k,14k,18k, 24k là gì.
There are many determinants of the quality and genuineness of gold. Color is an unreliable means of recognizing whether it is true or not. Gold items can vary from lustrous yellow to pale yellow. Color variations are usually due to presence of other metals. Pure gold usually throws a bright yellow hue, while a piece with palladium or zinc has pale appearance, thus the name white gold. Additions of copper give a characteristic reddish or rosy tinge, hence the name red gold. Nonetheless, the proportion of gold in the precious metal alloy determines the karatage.
Karatage of gold is tested using gold testing kits. These kits contain various tools, but the usual content is a set of test acids, a set of test needles, and a touchstone. You may also need to wear gloves during testing to protect your hands from the acids. Magnets and loupes can come really handy.
Usual testing may only require acids which are solutions of strong acids, like nitric acid or hydrochloric acid. These acids give reactions with typical metals like iron and copper but do not react with gold. However, a gold test kit contains different vials with different acid solutions for 10k, 14k, 18k, and 24k gold. A plain way to conduct an acid test is to get the appropriate acid. What it means is that if you are going to do a test for an 18k gold, get the vial with 18k test acid. You simply put a small drop of the test acid on a certain spot of the gold item. What you would want to see is the retention of color on that spot. If there is no color change, then that piece of metal is an 18 karat gold or higher. If a discoloration reaction occurs then most likely it is less than 18k.
You can do better testing with a touchstone which is a black stone with a somewhat rough surface. You rub gold against the touchstone until you see a golden streak on the black surface. You drop the corresponding acid. There should be no reaction if the gold has the right karatage. If the streak fades under the drop of acid then it contains less gold than the embossed marking says.