It is one of the most frequently asked questions and quite possibly one of the key misunderstanding in valuation of gold jewellery!
Gold trades live on the market and its price is usually represented as £ per troy ounce of fine gold.
Each ounce has 31.1035 grams and fine gold is 99.9999% pure, hence if gold is trading at say £1,450 per troy ounce then 1 gram of fine gold would be £1,450 / 31.1035 X 99.999% = £46.61 per gram.
You can use this handy web calculator to calculate price of gold in each carat.
Gold jewellery is made in different carats (that is purity or % of fine gold by weight) usually being 9 carat, 14 carat, 18 carat or 22 carat.
Table below shows usual carats in % of fine gold,
|Carat||% of Gold|
So if you have jewellery which is 9 carat, then there would be 37.5% of fine gold in it.
Lets say it weighs 10 grams then it would have 3.75gm (10gms X 37.5%) of fine gold. So, if gold price is £1,450 per troy ounce today then your jewellery would be valued as 3.75gm X £46.61/gm = $174.78