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It is not always easy to detect gold karat In this article we plan to answer your question about the gold Karat and how to determine it. In the following, we will concentrate on the concept of Gold and how to determine gold karat.
What is Gold Karat?
Gold Karat is is the pure gold existing in 24 parts of a piece of metal and the 100% pure gold Karat level is 24. The Karat level of Gold coins are of 21.6 and the gold which is used in producing jewelry is usually the 18 Karat gold.
Why isn’t 24-carat bullion used for making jewelry?
The main reason for not using 24-Karat gold bars is that it is so soft that can be deformed simply by the pressure of a hand. We should still remember that the final price of the product will be so high. Furthermore, calculating the gold price is usually done by the special price calculation formula.
Gold-Karat-Standard-in-Different-Countries
The amount of gold in jewelry pieces made by different countries is not the same, and each country has its own constant Karat level for producing pieces of jewelry. As an example 18 Karat gold is more often used in Iran and Italy. Its while some countries like Saudi Arabia and India consider 24 Karat gold as the standard purity level for gold. In America and Britain, 14 and 10 Karat gold are respectively the most popular types of gold.
How can we detect gold karat level?
24 karat gold is represented by 999, 18 karat gold by 750 and 14 karat gold is represented by 585. On some pieces of jewelry, you may notice letter K, which stands for Karat. Yet you may ask about the relationship between these numbers and gold Karat level. Here’s the answer.
The answer is easy. When the gold Karat is 18, it means that 750 parts of it are made of pure gold and the rest are made of other precious stones like silver, copper, and nickel. This is also true about 18 or 14 and even lower Karats of gold.
Different methods of detecting gold karat
Gold Karat can be checked by different methods like using touchstone and aqua regia, which is the traditional method. There are also other methods like using Spectrophotometer or coupling method.
Calculating Gold Grade with Touchstone.
Realizing the gold karat by touchstone is a traditional way, which is used in retail stores, only to distinguish gold from imitations. A touchstone is a black stone made of silicon and quartz and is resistant to the corrosive effect of acid.
This method is useful only to realize whether the thin layer on jewelry is gold or not. To figure out different karat levels, for high grades or those higher than 14, the piece, the piece should be drawn on quartz or touchstone.
Lower Karats of gold which are the pieces with Karat levels of less than 14, should be calculated with pure nitric acid, at different concentrations and Karats higher than 14 will be checked by aqua regia or a combination of nitric acid and sodium chloride.
How can we determine karat level using a spectrophotometer?
Another method for realizing gold karat level is using a spectrophotometer which measures the intensity of light as a function of wavelength. In this machine, electromagnetic radiation in the visible and ultraviolet region is absorbed by gold, and the amount of gold or actually the gold grade is determined based on the intensity of absorption. The machine makes it possible to calculate the gold Karat by using a Tungsten lamp and a UV spectrophotometer together with a deuterium lamp.
Determining Gold Karat by Laser Scanning or XRF.
In a specialized method, these machines can detect gold karat level in less than 30 seconds which is the fastest way to distinguish all existing metals in the alloy. To do so, you need to put your piece of gold in the machine tank, and after a few minutes, the machine will show you the alloy content and also the karat level.
Calculating Gold Karat Level by Scanning
Scanning is usually the best and most accurate method that is done in gold grading laboratories. This method is as follows.
- Sample Smashing The sample should be smashed completely to pieces as small as 80 mesh.
- First Melting Melt the ground sample until the metal is separated completely
- Coupling In this level, gold and silver will be removed from lead by the coupling machine.
- Acid Work Silver can be solved in nitric acid and the result will be pure gold.
- Weighing: Finally, the pure gold will be weighed by electronic scales, and the gold Karat can be calculated in comparison with the initial sample.
The Most Accurate Approach: Coupling
To determine the gold Karat, there will be a need to a 3 to 1 ration of gold and pure silver. If the gold understudy is copper-free, 50 grams of copper should be added to the combination and the whole combination should be wrapped in pure lead sheets.
The lead ball will be placed in furnace at 1050 centigrade degrees, and after taking them outside, they will boil in nitric acid for 90 minutes. The gold resulting from this procedure should be weighed again. The final weight difference shows the gold Karat.
Here’s an example for a better understanding of how the whole process goes.
The ball made by wrapping gold in a sheet of lead should be placed in the couple tank at 1050 centigrade degrees. When it got melted and became bright, the furnace will be turned off and the temperature will be decreased to 850 centigrade degrees.
In the next level, the wrapped ball which was placed in the couple and contains gold and other valuable metals will boil in a beaker containing 20 milliliters of nitric acid for half and hour and the brown gases will leave completely. This procedure should be repeated several times so that all the extra metals will be removed from gold.
The resulting gold which looks brown, will be heated again at 800 centigrade degrees to make it very bright. Then we weigh it again to find the weight difference between the initial weight and the current piece and determine the gold Karat,
The final point about gold karat grade
In this article, we suggested 5 methods for distinguishing gold Karat, the easiest one of which is using the touchstone that usually has a high error coefficient. Other methods suggested in this article, usually necessitate accurate laboratory equipment. To buy jewelry, and making sure about the Karat of the piece of jewelry you are buying, we suggest you visit our pieces at EG jewelry store.
