Went to Jewelers to buy gold. The family member with me who owed me money payed small token advance on my behalf to jewlers even though I didn't intend or want to. Had to pick gold next day and pay rest. Was there any sin on me and is all of that gold haram now?

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

If what happened between you and the jeweler was merely a promise to buy jewelry from him, then there is no blame on you for that, and it is not affected by the fact that your relative paid some money to him on your behalf.

But if what happened between you and the jeweler was that you bought the jewelry from him on the condition that you would give him the price later, then this is not permissible according to the majority of scholars. They stipulate that the exchange take place in the contract session, and some jurists are of the view that the jewelry is permissible to be sold and bought for later payment, and the exchange is not required in it because the industry excluded gold from cash, and it became a commodity that could be bought and sold on the spot and on credit, like clothes and other commodities. This is the choice of Sheikh Al-Islam Ibn Taymiyyah . Therefore, the transaction is valid based on this saying, and there is no blame on the one who imitates it.

However, if the aforementioned debtor pays some of the price, it has no effect on the transaction between you and the jeweler.

Then, what that debtor paid on your behalf, if he intended it to pay for some of your debt, then there is no problem with that, and if he intended it as a gift to you, the jurists differed regarding the ruling on accepting the debtor’s gift before paying the debt. Some of them said it is forbidden, and some of them said it is disliked, and there is no doubt that it is better and more prudent not to accept this or any other gift from him before paying the debt unless it was the custom between you to give gifts before he became your debtor.

Allah knows best.