Carbon spots in smoked opal.
Translucent Black Play-of-Color Opal Stone Cabochon, Heat-Treated
Carbon spots in smoked opal.
Article: Opal Treatments: How to Detect Treated Opals
| Gemstone | Opal Stone |
| Treatments | Heat Treatment |
| Natural or man made | Natural |
| Gem State | Cabochon |
| Color | Black |
| Transparency | Translucent |
| Photo phenomena | Play of Color |