Hi All Looking through my old indian head book that has been in a box for 30 years!! I see people here post rainbow toned pennies and noticed these 3 in a row, when held at an angle show a rainbow specular - - Is this considered rainbow tonight, or is that only if it is visible from looking head on? Out of all of them, just these 3 have this!
They are toned, but not what collectors are after. Those have been harshly cleaned in the past, stripped of patina to bear metal, and now that metal is starting to retone. Much different then high grade coins with mint luster that tone and produce iridescent colors. Same process, different starting point.
Interesting!!! How can you tell they have been cleaned? Must have bought them that way as I forgot about them for near 30 years
Cleaned copper can retone into some wild looking colors. It would be interesting to see the reverse of those coins.
You can tell in part because of the crazy colors on low grade coins. But in general, copper develops a patina over time and that patina has a specific look. The patina differes over the coin, protected areas have more patina compared to raised areas due to wear. Here is an extreme example from my collection, but the same occurs on modern copper coinage.
Toning only visible at a certain angle is common and a lot of the toned coins you'll see photos of are essentially glamor shots showing them in the best possible light. If you'd really like to learn there's nothing like experimenting. Simply take however many pre-82 cents and go to town. You can try to clean then using whatever different methods that come to mind and later try to re-tone them doing the same. The value in such exercises isn't so much to learn about the coins you've shown here, but to help you down the road.
