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So many times our customers have asked whether 9CT gold is harder than 18CT gold. Precious Metal Technologies have the answer.
“It is surprising for most people to learn that the simple answer is no. It would be fair to assume that this confusion has arisen due to the fact that pure gold is known to be quite soft, too soft, in fact, to be used successfully in local jewellery. 18CT obviously contains twice as much gold as 9CT, the assumption being it is therefore softer….
There are many different combinations of metals which can be used to make gold alloys with each combination having specific characteristics. This can be further influenced by mechanical working and/or heat treatments, however, most common 18CT gold alloys are both harder and more hard wearing that their 9CT equivalent.
Alloy |
As Cast Hardness |
Max.Annealed Hardness |
9CT |
70-105 |
160-170 |
18CT |
85-125 |
170-230 |
The “Vickers” hardness test method (as shown by above table) consists of indenting the test material with a diamond indenter then establishing the relationship between the load applied and area of indentation.”
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