Saffron
Gold is tremendously more expensive than titanium.
You are wrong. Copper is NOT more expensive than gold.
gold is more expensive than iron simply because iron is more common and gold is also a purer metal
Pure yellow gold is more expensive than an alloy.
No, gold is more expensive than silver as it is more rare
yes platinium is much more expensive than gold
Platinum is more expensive than gold because of the difficulty associated with mining it. Platinum is harder to mine than gold, which means it requires more energy and effort to extract.
White gold can cost a little more than yellow gold but not prohibitively so.
Platinum
Yes.
No, gold is around twice more expensive than iridium.