trading gold and silver for less in weight is not allowed but I have gold and I want to buy jewellery from it if I trade the gold for money I will get maybe 95% of the worth of gold but if I trade for jewellery I may get 98%. is this predicable? and if it has diamonds in it does this not apply?

Ustadh AbdulAziz al-Haqqan

No, exchanging your gold for the jewelry is ribā even if it gives you a better rate. Sell your gold for money, take the price, then buy the jewelry with it in a separate sale. Diamonds do not change this must first be separated though.