This quahog pearl grades in color from white to a medium deep purple. © Kojima Pearl. Used with permission.
Opaque Purple Calcareous Concretions Rough
This quahog pearl's color goes from white to a medium-deep purple. © Kojima Pearl. Used with permission.
Article: Quahog Pearl Buying Guide
Credit: Kojima Pearl
| Gemstone | Calcareous Concretions |
| Natural or man made | Natural |
| Gem State | Rough |
| Color | Purple, White |
| Transparency | Opaque |
| Multi-color | Bi-color |