In most countries around the world the purity of gold alloy is usually stamped or lasered on the jewelry. The quality or standard of gold purity is often managed by the local assay office, which tests the quality of the metal used.
In the UK and Europe there are strict standards regarding these tests and jewelry that passes is given an Assay Hallmark. This mark is used not only for gold, but also for Platinum and Sterling silver.
In 1973 legislation was brought into the EU to standardize controls of precious metals. Countries participating in this system test the metals to a common standard stamping or lazering the metal that reaches the required standard with a Common Control Mark (CCM), attesting to the material's fineness. The motif of the CCM is the balance scales, superimposed, for gold, on two intersecting circles; for platinum, a diamond shape and for silver a mark in the shape of the Latin letter "M".
This mark is used in the following countries: Austria, Cyprus, the Czech Republic, Denmark, Finland, Great Britain, Hungary, Ireland, Israel, Latvia, Lithuania, the Netherlands, Norway, Poland, Portugal, Sweden, Switzerland and Ukraine
The most significant item currently up for debate is the recognition of palladium as a precious metal. Some member nations recognize palladium as a precious metal while others do not
Chart showing the density of comparative precious metals.
Weights & Measurements
In many countries around the world, jewelry metal is weighed in grams. However the commodities market value precious metals in troy ounces and in the USA precious metals are also measured in penny weight DWT.
The following conversion table in shows the formula: