What is a Red Copper Coin?

We receive a lot of questions about what constitutes a so-called Red copper coin. For many, Red is the most desirable coloration on a copper coin, yet it’s also among the scarcest, particularly when considering vintage copper coins.

Any advice for growing a red cuprous oxide layer on a copper U.S. penny? Trying to make a crystal radio rectifier. : r/chemistry

What Color is Your Copper Coin? - Grading Them

Copper Coin Hair Is the Most Natural Twist on Red—Photos

Oldest red copper coin you've seen?

BOOK REVIEW: GRADING GUIDE FOR EARLY AMERICAN COPPER

What Does Red Mean in Penny Grading? - APMEX

1993 CHINA RED COPPER PANDA 5 YUAN COIN - The Coin Connection

What Color is Your Copper Coin? - Grading Them

Price Differences for Brown, Red Brown and Red Coins

The All-Time #1 Lincoln Cent Proof Set “Red Copper Collection” to be Auctioned by GreatCollections

5 Copper Coins That Could Be Worth a Fortune