Gemstone Treatments & Enhancements Flashcards

Which treatment is most commonly applied to rubies and sapphires to improve their color and transparency?

Answer: Heat treatment

Heat treatment is the most widely used enhancement for corundum gemstones, improving both color and clarity by dissolving rutile silk and altering trace element chemistry.

Which organization publishes internationally recognized disclosure guidelines for gemstone treatments used by the trade?

Answer: CIBJO (World Jewellery Confederation)

CIBJO publishes the internationally recognized Blue Books, which establish gem grading nomenclature and disclosure standards for treatments accepted by the global jewellery trade.

Fracture filling in diamonds to improve apparent clarity is most commonly accomplished using which substance?

Answer: High-lead-content glass

High-lead-content (lead) glass is injected into fractures to fill them; its refractive index close to diamond's makes the fractures nearly invisible, but the process is non-permanent.

What does the acronym HPHT stand for in the context of diamond color treatment?

Answer: High Pressure High Temperature

HPHT (High Pressure High Temperature) treatment subjects diamonds to conditions that mimic the earth's mantle, permanently altering color by annealing structural defects responsible for undesirable tints.

Beryllium diffusion treatment became a major trade concern in the early 2000s and is primarily associated with which gemstone?

Answer: Sapphire

Beryllium diffusion of sapphires was discovered around 2001–2002; the light element penetrates deep into the stone, producing dramatic orange, yellow, or padparadscha-like colors undetectable by standard gemological testing.

Which gemstone is most widely treated with oil or resin fracture filling, making undisclosed treatment a common trade concern?

Answer: Emerald

Emerald is routinely fracture-filled with oils, resins, or polymers because the species almost universally contains surface-reaching fractures (jardin); the practice is so common it has its own grading scale.

Which type of treatment involves exposing a gem to gamma rays, neutron bombardment, or electron beams to permanently change its color?

Answer: Irradiation

Irradiation alters the color center defects in a gem's crystal lattice by exposing it to nuclear radiation, producing new or intensified colors that may or may not be stable without subsequent heat treatment.