In Singapore, the term “90 purity test” typically refers to a test conducted to determine the purity of gold or other precious metals. It is commonly used in the context of buying or selling gold jewelry or bullion.

The purity of gold is measured in karats (kt) or fineness. Karat purity measures the amount of pure gold in a piece of jewelry, with 24kt being the highest level of purity. Fineness, on the other hand, measures the proportion of gold content in parts per thousand.

The “90 purity test” specifically suggests that the gold being examined has a purity of 90%. In other words, it indicates that the gold item contains 900 parts of gold out of 1000. This level of purity corresponds to 21.6 karats in the karat system. It means the gold is 90% pure and has a small amount of other metals mixed in, such as copper or silver, to enhance its durability and strength.