Some of these pearls show the unusual "eye" effect. Kari Pearls. Used with permission.
Opaque Purple Cat’s Eye Calcareous Concretions Rough in Necklace
Some of these pearls show the unusual "eye effect." © Kari Pearls. Used with permission.
Article: Quahog Pearl Buying Guide
Credit: Kari Pearls
| Gemstone | Calcareous Concretions |
| Natural or man made | Natural |
| Jewelry type | necklace |
| Gem State | Rough |
| Color | Purple, White |
| Transparency | Opaque |
| Photo phenomena | Chatoyancy |
| Multi-color | Bi-color |