“...a silver-plated crown...”
THAT is interesting! How did they do it?
One startling discovery in ancient Sumer’s ruins was the existance of batteries. Crude batteries using wine vinegar as the acid, but real.
This battery-pwered electricity was used by Sumerian craftsmen to plate precious metal on copper.
Not a lot of details in the article on how plating was done by the Sican’s, but it is courious nonetheless.
It was probably gilded, not plated. The Lambayeque culture was very advanced in metallurgical knowledge, like their neighbors the Moche. The Moche probably were more advanced but there appears to have been extensive exchange of metal-working technology in that entire region.
This is from a scientific paper on the Moche:
"Metallurgical studies of a group of gilt copper objects from Loma Negra have shown that the gilding was achieved by an electrochemical replacement plating process in which gold and silver are dissolved in an aqueous solution of corrosive minerals. The precious metals are then plated from solution onto the copper objects. Moche metal craftsmen can now be credited with having developed the two most sophisticated of Andean gilding procedures: depletion gilding and electrochemical replacement plating."
Those people were damned smart. I've seen an exhibition of their gold and silver work and it was amazing. I'm a silver and gold-smith so I'm not exactly unfamiliar with the topic.