RSorder is the best site to purchase RuneScape Gold (both OSRS and RS3). Based on my experiences (12 years of RMT as an occasional buyer and seller) I have discovered this to be one of the safest site in the business. It allows you to trade only among other customers, and this means the prices extremely affordable, and transactions are safer. It's impossible to determine which is the source from the metal however If you could find a seller who is legitimately selling gold, it would be RSorder or another marketplace site. The majority of stores online will offer something similar.