You try

"Umm, hi." You say with a gulp, suddenly nervous. "I'd like to sell this." You set the chest on the counter and open it for her to see.

"Where the fuck did you get that!" She yells taking a step back clearly terrified. "You are just a low level...". She stammers on staring at you, "Unless you are blocking..." She smooths down her hair in an obviously nervous manner, "I am so sorry miss, um, I would love to see your cool old crown." She steps forward and bends in to get a closer look. "How much do you want for this priceless artifact that can end all of existence?"

"Oh, wow. So this is...". You say back to her and take a step back. "So I shouldn't sell it then?"

"Sell... lady if you close the lid and go right now I'll give you this ruby, as long as you promise not to kill me."

"Oh." You say looking at the ruby.