The cuprites from the Rubtsovskiy Mine in Russia are widely considered the best ever found. The Rubtsovskly Mine is an operating copper mine, and the oxidation zone has produced Cuprites, Azurites, native copper, silver, and iodine minerals like Miersite. I have been following the production for the last two years, to better understand how these are unique and what pieces stand out from "the crowd." About 95+% of the production have damage of some kind to a corner or edge. This is largely due to the miners who when extracting crystals from the kaolin clay zone (which protects the Cuprites), they drop them into their pockets, and they get dinged. 

 These shiny blocky cuprites have a good thick section of spongy silver on the back (rare occurence worldwide). It weighs 37 grams.