Which term refers to the flash of changing color seen in a fracture-filled diamond when viewed parallel to a filled inclusion and rocked under magnification?

Which term refers to the flash of changing color seen in a fracture-filled diamond when viewed parallel to a filled inclusion and rocked under magnification?

• A. Finish
• B. Fire
• C. Flash effect
• D. Fracture filling

Answer: (C)

The flash effect is the term for the rapid color shifts you see in a fracture-filled diamond when you view it parallel to the filled inclusion and rock the stone under magnification. This happens because the filler in the cracks has a different refractive index than the host diamond, so light interacting with those filled cracks creates dispersion and interference that change as the orientation changes. As you rotate the diamond, different wavelengths are enhanced or diminished along that plane, producing a distinct, changing flash of color. This is different from the general fire you might see in a diamond, which is the broader dispersion of colors across the stone, and it’s not about surface polish (finish) or the treatment itself (fracture filling) but about the specific light behavior along the filled cracks when viewed in that orientation.

The flash effect is the term for the rapid color shifts you see in a fracture-filled diamond when you view it parallel to the filled inclusion and rock the stone under magnification. This happens because the filler in the cracks has a different refractive index than the host diamond, so light interacting with those filled cracks creates dispersion and interference that change as the orientation changes. As you rotate the diamond, different wavelengths are enhanced or diminished along that plane, producing a distinct, changing flash of color. This is different from the general fire you might see in a diamond, which is the broader dispersion of colors across the stone, and it’s not about surface polish (finish) or the treatment itself (fracture filling) but about the specific light behavior along the filled cracks when viewed in that orientation.