Assay means the analysis of precious metal component in an alloy, a piece of art or jewelery. This is a rather technical job, and it really is carried out only by authorized institutions that have the best and relevant equipment to test the precious metal content. Such institutions are called Assay Offices. After performing the necessary process of assaying bullion, they certify the claim of the maker about its quality/purity by stamping a Hallmark on it.
Hallmarks are special symbols that stand for some particular factor. For example, a 750 stamp means 18k gold; and 999 means 24k gold. There are a lot of techniques for assaying gold or bullion: the touchstone strategy, X-Ray florescence and Cupellation. Each of these techniques determines the fineness of the gold item, as claimed by the manufacturer.
The Touchstone technique is employed in cases where the item under analysis is particularly rare or precious. Touchstone is a special assaying tool which determines the fineness of the item up to 10 to 20 parts per thousand, precisely. The item under question is rubbed with the touchstone and then removed. The touchstone is then treated with acids or chemicals and the colour distinction is studied with the aid of references.
This procedure, having said that, isn’t advised for white gold analysis because the colour variation among the white gold alloys cannot be differentiated that easily. This is among the oldest techniques of assaying gold and bullion.
X-Ray florescence technique is a latest and quite fast strategy of assaying gold items. It truly is also employed mostly on precious gold pieces which cannot be destroyed by other approaches of assaying. This approach is ideal for flat and large surfaced items. It does not take extra than 3 minutes to test the metal and it generates a laptop or computer print of the test result.
Another advantage of this technique is that it tests the composition of the other components present within the alloy. There are some contraindications for this strategy as properly. Those gold goods that are treated with chemicals or have gone by way of electroplating need to not be assayed with this technique.
Probably the most accurate approach of assaying gold is Fire Assaying or Cupellation. This is also a entirely destructive technique of assaying. It gives the fineness of 1 part of gold per thousand accurately. This is an internationally recognized approach of assaying and is employed commercially for assessing the quality of gold ores. Major refineries and gold mining companies use this technique for analyzing the purity, fineness and quality of gold ores.
Gold and silver coins are also assayed by the appointed assay offices. This was important at a time when gold and silver coins had been uses in daily commerce; nowadays, the use of gold and silver coins as currency is suspended in many countries of the world. But gold coins are still available for small scale investment purpose or as a means of exchange of gifts on special occasions. There are local gold assay offices everywhere inside the world that can come across out the purity of the gold items which you wish to get assessed.