"Those are ragging grey diamonds! They're supposedly only known in legends!"(shocked while sounding professional / calm) (fplease don't make this seem cheesy as best as you can). (Give it a a genuine response if you had discivered something ground breaking)

"Where in the world did you even manage to aquire that from?"(clamed and professional) 

I have no intention to remotely be around someone as high bountied anymore. Get the diamonds and your desideratum is to forget I'm even here and run to safety. (Nervous)