DCA Diamond Treatments & Enhancements 2 — Questions and Answers
Question 1: Which of the following diamond colors can be produced through irradiation treatment?
- Only colorless (D-F range)
- A wide range including blue, green, yellow, and pink (Correct answer)
- Only brown shades
- Only black diamonds
Correct answer: A wide range including blue, green, yellow, and pink
Irradiation can produce a variety of fancy colors including blue, green, yellow, orange, and pink by altering the diamond's crystal lattice.
Question 2: Under magnification, how can a gemologist detect laser drilling in a diamond?
- By observing a flash of color along the drill path
- By finding a thin white tunnel or channel leading to a dark inclusion (Correct answer)
- By detecting a hardness reduction in the drilled area
- By identifying a refractive index mismatch at the surface
Correct answer: By finding a thin white tunnel or channel leading to a dark inclusion
Laser drill holes appear as thin, worm-like or straight tunnels visible under magnification, often leading from the surface to a dark inclusion.
Question 3: Which characteristic of a fracture-filled diamond may change over time or with exposure to chemicals?
- Its carat weight
- Its surface hardness
- The apparent clarity improvement from the filler (Correct answer)
- Its refractive index reading
Correct answer: The apparent clarity improvement from the filler
The glass-like filler can be damaged by heat, chemicals, or ultrasonic cleaning, causing the treated fractures to become visible again.
Question 4: The Yehuda process is a well-known proprietary method for which type of diamond treatment?
- HPHT color enhancement
- Fracture filling (Correct answer)
- Laser drilling
- Surface coating
Correct answer: Fracture filling
The Yehuda process, developed by Zvi Yehuda, is one of the most recognized fracture-filling techniques using a proprietary glass-like substance.
Question 5: Which type of diamond treatment is generally considered permanent and does NOT require ongoing disclosure concerns about stability?
- Fracture filling
- Surface coating
- Laser drilling (Correct answer)
- Polymer impregnation
Correct answer: Laser drilling
Laser drilling creates a permanent physical alteration to the diamond's structure, unlike coatings or fillers that can degrade or be removed.
Question 6: How does surface coating on a diamond typically appear when examined under a loupe or microscope?
- It appears as a deep internal haze
- It may show as a thin film, abrasions, or color concentration at facet junctions (Correct answer)
- It creates a distinctive star pattern at the culet
- It causes a double refraction visible through the table
Correct answer: It may show as a thin film, abrasions, or color concentration at facet junctions
Coating is applied to the diamond's exterior and may chip or wear at facet edges, appearing as a thin film or color pooling at facet junctions under magnification.
Question 7: If a diamond has been irradiated and then annealed, what is the likely reason for the annealing step?
- To increase the diamond's hardness rating
- To stabilize and modify the color produced by irradiation (Correct answer)
- To remove the laser drill channels created during treatment
- To fill internal fractures with a glass-like substance
Correct answer: To stabilize and modify the color produced by irradiation
Annealing (controlled heating) after irradiation is used to stabilize the new color and can shift it to a different hue, such as turning blue-green into a more desirable yellow or pink.
DCA Diamond Treatments & Enhancements 2
Which of the following diamond colors can be produced through irradiation treatment?