| The specimens collected by Mr. Schoolcraft, vary much in the color of the nacre. |
| In a similar fashion, pearls and abalone shells are iridescent from the interference caused by reflections from multiple layers of nacre. |
| The pearls are polished by shaking them together in a bag with nacre powder. |
| Natural nacre also benefits from so-called sacrificial ionic bonds between proteins, which break under stress but can reform. |
| Continuous layers of nacre grow like onion skins around the particle. |
| The value of the pearl is based on the brilliancy of the nacre, the size, and the form. |
