I suggest you buy your gold jewellery from Australian based sellers. Jewellery sold within Australia from a repuatable dealer will have a hallmark. Ask the seller what the hallmark is. Avoil buying jewellery that has GP in the hallmark (gold plating) Ask the seller for weights. When buying gold chain and bracelets, take the total price and divide it by the weight,. That gives you a price on how much per gram you are paying. EG. If a 9ct gold bangle weighs 50grams and you paid $1400 for it, you paid $28 per gram.
Use this as a guide for buying chain and you will shop wiser!